PDA

View Full Version : Film test results



macandal
23-Mar-2014, 13:35
I know film testing is very personal, but I want to compare notes with any of you who may have been used the same film/developer combination. In the past I've screwed up this test so badly, so I want to make sure I've done it right.


I am testing Delta 100 (4x5) with Ilfotec DD-X.
I kept the temperature at 68F.
I used the development times suggested by the Ilford tech sheet for this film (http://www.ilfordphoto.com/Webfiles/201062894918374.pdf) which was 12 minutes intermittent agitation.
I used the nikor tanks to develop the sheets.
I used the Ansel Adams method as it appears on The Negative (using third stops--my lens indicates these third stops)
I left the shutter speed constant and changed the f stops.

My results showed that my personal EI for this combination is 160.

Are my results comparable with those some of you may have had?

Thanks.

Leigh
23-Mar-2014, 14:50
Hi Mario,

I expect your results are correct for you, assuming the tests were done correctly.

Film speed will vary from one batch to the next. It's affected by shutter speed errors and other factors.

That being the case, the results are quite personal indeed.

- Leigh

Bill Burk
23-Mar-2014, 16:38
Hi Mario,

The speed you found is higher than I would expect when testing for Zone System speed. But at this point you haven't determined developing times. You might have developed longer than "N".

So take it for now, use the speed you found to go on to the next phase of testing, finding the development times.

You might find your "N" time is less than 12 minutes, and if so, the fact this test set was developed longer than "N" could explain your "atypical" speed result.

Leigh
23-Mar-2014, 17:58
The shutter speeds have not been tested, nor has the aperture.

Given that shutter speeds can vary 30% from nominal, that error could account for
over 50% of the difference between expected and calculated film speed.

Aperture error and differences in processing methodology could easily eat up the other half.

The bottom line is that we can't obtain any definitive information from the data presented.

Personal film speeds are exactly that... personal. There are myriad factors that affect those numbers.

If you want to do highly-controlled testing with thousands of sheets of film, you'll come up with the manufacturer's number. That's true because that's exactly how they got the number in the first place.

The concept of "personal ASA" is simply shorthand for the corrections required to your processes and
equipment that are needed to produce negatives with the same characteristics as the manufacturer.

- Leigh

Bill Burk
23-Mar-2014, 18:59
Let me clarify...

Normally people who rate film using the methods in Ansel Adam's "The Negative", find a personal exposure index that is less than the manufacturer's ISO speed.

I would have said there was something wrong for Mario to get 2/3 stops above manufacturer's ISO rating for the film.

But I noticed Mario developed according to manufacturer's instructions. The development to manufacturer's specification probably helped Mario achieve manufacturer's close to ISO speed.

So the fact Mario's "system" results in a plus 2/3 stop difference is not a surprise. For amateur purposes, plus or minus 2/3 stop could be considered "in control".

Like you say, Leigh, we don't have enough information to conclude anything. A shutter speed alone could cause this.

But if Mario still gets 160 as an end result of Zone System, I'd be concerned it's off a whole stop from what I expect.

Let's see how much the speed falls when Mario develops for "N".

Leigh
23-Mar-2014, 19:14
Let's see how much the speed falls when Mario develops for "N".
Realize that the exercises required to determine "N" are in fact compensating for errors in the personal system.

- Leigh

Bill Burk
23-Mar-2014, 20:20
Mario,

Getting back to your original request: I haven't tested that combination. I'm testing 35mm 100TMAX in D-76 tonight, soon as the water hits 68*F. I'm using sensitometry (exposed film using flash, EG&G at 10^-2) instead of camera tests and will develop in D-76 straight for 12, 24 minutes... and in D-76 1:1 for another series of times. The film and D-76 are fresh.

I expect I will get slightly less than rated speed because my techniques are not fully ISO-compliant.

macandal
24-Mar-2014, 00:53
I read somewhere (of course now that I want it I can't find it) that this film/developer combination should give me a personal EI below the stated ISO (80 or so) so when I got 160 I worried a bit. The lens I used has been calibrated so I trust my shutter speeds. I developed according to manufacturers instructions because ... well, because that's where one starts right? What else was I supposed to do? Guess? You start according to what the manufacturer tells you with your film/developer combo. I don't understand what else was I supposed to do? The only thing I may have done "wrong" is that I was going over my film development instructions and it said to agitate constantly for the first minute and then for 10 seconds every minute thereafter. Could one minute of constant agitation could have affected my final result?

Seriously? No one has ever done a film speed test using the film/developer combo I used? I would love to compare notes with you elusive guys.

Thanks.

(I don't want to retest if I don't have to because this is expensive film, but I will do it if I have to.)

Leigh
24-Mar-2014, 05:31
The only thing I may have done "wrong" is that I was going over my film development instructions and it said to agitate constantly for the first minute and then for 10 seconds every minute thereafter.
Disregarding technical issues like shutter speed accuracy, the major difference between manufacturer's speed and
personal speed lies in the development, both the choice of developer and the actual processing technique used.

The lower ASA that's commonly found supports the idea of "expose for the shadows, develop for the highlights" by
slightly increasing the exposure.

If you have reasonable shadow detail in your images (light grays rather than completely clear negative areas) at
your higher ASA, they your negs should print fine.

The most important test of any technique is whether you can easily make good prints from the negatives.

- Leigh

macandal
24-Mar-2014, 08:33
If you have reasonable shadow detail in your images (light grays rather than completely clear negative areas) at
your higher ASA, they your negs should print fine.

The most important test of any technique is whether you can easily make good prints from the negatives.

- LeighI'm not there yet, so I won't know that yet. I was trying to avoid further testing before I knew that my film speed test had been done right. At this point I'm not moving forward until I am certain I have done it right. I understand that this type of testing will yield a personal result (i.e., that it will vary from person to person), I cannot be that far off from someone using the same film/developer combination I have used and a similar agitation method. That's why I would love to compare results with other folks who have tested this in a similar way.

I do appreciate everyone's input, though.

Thank you Leigh and all.

ic-racer
24-Mar-2014, 11:39
How are you determining your ISO 160 frame or sheet is the correct "Zone I" exposure? I suspect you may have made an error in math when making or recording or reading your negative.

macandal
24-Mar-2014, 12:03
How are you determining your ISO 160 frame or sheet is the correct "Zone I" exposure? I suspect you may have made an error in math when making or recording or reading your negative.ic, it's on my first post. I am using sheet film (4x5). I'm using the method described in The Negative by Ansel Adams where the net density reading (density - film base+fog) closest to 0.1 is Zone I.

macandal
24-Mar-2014, 13:43
I left the notebook where I took my notes at home. I'll post my results tonight, when I get home.

macandal
24-Mar-2014, 13:51
Hi Mario,

The speed you found is higher than I would expect when testing for Zone System speed. But at this point you haven't determined developing times. You might have developed longer than "N".Yes, but what about the faster than normal rating my testing gave me? I was expecting this to be below the stated 100 ASA rating. I was expecting it to be 80 or 50 or somewhere in between. The 160 EI was a surprise even to a novice like me?

Thanks.

Leigh
24-Mar-2014, 15:20
ic, it's on my first post. I am using sheet film (4x5). I'm using the method described in The Negative by Ansel Adams where the net density reading (density - film base+fog) closest to 0.1 is Zone I.
I think you want to select a negative where the density exceeds the (base+fog) by 0.1 units.

- Leigh

macandal
24-Mar-2014, 15:56
I think you want to select a negative where the density exceeds the (base+fog) by 0.1 units.

- LeighRight. You are describing the net density.

macandal
24-Mar-2014, 20:15
Here are the results of my test:



Ilford Delta 100 + Ilfotec DD-X
68F
12 minutes, intermittent agitation
Source: The Negative by Ansel Adams

Zone V: f5.6 1/60





ASA
f
Shutter
Density
No Density


1.
No exposure (blank)
--
--
--
0.17
--


2.
Zone I
100
22
1/60
0.37
0.20


3.
1/3 stop less than #2
125
22 1/3
1/60
0.31
0.14


4.
2/3 stop less than #2
160
22 2/3
1/60
0.26
0.09


5.
Zone 0
200
32
1/60
0.22
0.05


6.
1/3 stop more than #2
80
16 2/3
1/60
0.40
0.23


7.
2/3 stop more
64
16 1/3
1/60
0.48
0.31


8.
Zone II
50
16
1/60
0.57
0.40

Leigh
24-Mar-2014, 20:44
I sure don't understand that chart.

The negative density drives the zone correlation, not the other way around.

The chart should be in order by negative density, not bouncing around.

In this case, line 4 should be labeled Zone I, not line 2.

- Leigh

Kevin J. Kolosky
24-Mar-2014, 21:28
1. place a black card in shade
2. meter it
3. close down 4 stops (zone 1)
4. focus at infinity
5. make the exposure
6. develop normally
7. read the negative on the densitometer
8. note where the reading is in relation to film base plus fog
9. If not .10 above interpolate by 1/3 stops (remembering that .30 on densitometer equals 1 stop - exposure is recorded in terms logarithms and the log of 2 is .30)

Bill Burk
24-Mar-2014, 23:12
Hi Leigh,

The graph makes sense with Ansel Adam's book in hand. Negatives are exposed as if metered at rated speed, and that reading placed on Zone I. The remaining rows have test exposures relative to that Zone I at Box Speed shot. It's an arbitrary test sequence, not organized sequentially. Mario found a negative which meets the 0.10 over B+F criterion at an exposure 2/3 stop less than Zone I placement at Box Speed, which makes the test result indicate rated speed 160.


I think Mario's development is correct. But I would say the variables of the camera/lens/meter/shutter/flare which are also included in Mario's test (because of the nature of Ansel Adams' instructions) amounts to nearly +2/3 stop.

Mario, I'd be very cautious before choosing EI 160 for a 100-speed film.

Here are my test results with 100TMAX and D-76. I only achieve a 160 speed when I develop in stock D-76 undiluted for 24 minutes, and I barely hit 200 in 48 minutes.

http://www.beefalobill.com/images/tmxfamily.jpg

macandal
24-Mar-2014, 23:37
Mario, I'd be very cautious before choosing EI 160 for a 100-speed film.Yes, Bill, I know. That's why I don't want to go any further with the testing until I'm certain I got it right.

So, Bill, what do you suggest I do? I don't want to keep experimenting with this film because it is not cheap, so I want to make sure that the next time I test, I get it right. My professor in a zone system class I took a while back used a Zone II method (as opposed to Ansel's zone I method) of testing.

So what could I have done wrong? Did I develop too long? However, that's what Ilford recommends for this film/developer/temperature combination. I thought that was the starting point of any zone testing: the recommended time for the combination.

Hmmm? What to do?

Thanks.

macandal
24-Mar-2014, 23:40
1. place a black card in shade
2. meter it
3. close down 4 stops (zone 1)
4. focus at infinity
5. make the exposure
6. develop normally
7. read the negative on the densitometer
8. note where the reading is in relation to film base plus fog
9. If not .10 above interpolate by 1/3 stops (remembering that .30 on densitometer equals 1 stop - exposure is recorded in terms logarithms and the log of 2 is .30)This sounds like the testing I did.

Leigh
24-Mar-2014, 23:48
1. place a black card in shade
2. meter it
3. close down 4 stops (zone 1)
Solid black is Zone 0, not Zone 1.

If you make that correction, the OP's speed works out to be 80, not 160.

- Leigh

Leigh
24-Mar-2014, 23:50
Hi Leigh,
I'd be very cautious before choosing EI 160 for a 100-speed film.
Hi Bill,

I would be suspicious also.

That's why I made the correction in post #23, which puts the ASA right where it belongs at 80.

However, as I said earlier, the only real test is to go out and shoot stuff, and evaluate the results.

- Leigh

ic-racer
25-Mar-2014, 07:47
This sounds like the testing I did.

If everything checks out your personal EI is what it is. You, of course, did not do an ISO test. The reason one tests for EI is to take into account the way you meter and slow shutters, and meters that are off etc.

I'd just double check it with your next batch of film before you do your development tests. That is, shoot a few different uniform objects in different lighting conditions and place them on zone I. See that you densities are still around 0.1 log d on the processed film.

Bill Burk
25-Mar-2014, 07:57
Solid black is Zone 0, not Zone 1.

If you make that correction, the OP's speed works out to be 80, not 160.

- Leigh

No, that's not it, anything you meter becomes Zone V.

Bill Burk
25-Mar-2014, 09:56
Leaf shutter speeds are calibrated to include the whole bell curve of illumination that happens during opening and closing fully. At f/29, your shutter speed is longer than the shutter speed would be at f/5.6, because the entire aperture at f/29 is opened very quickly.

Maybe your shutter speed is effectively 1/40 second at f/29... If so, the exposure index you found, EI 160, compensates for the exposures you make at the shutter speed and f/stop combination of 1/60 and f/29. This would be a valid interpretation of your test results. I say you have good test process but the test steps you followed lead to results that are valid for that specific shutter speed and f/stop only.

I recommend that you use EI 100 for other f/stop and shutter speed combinations when you develop for 12 minutes. If you develop for less than say, 10 minutes, to pick an arbitrary cutoff, use EI 80.

macandal
25-Mar-2014, 10:00
Maybe your shutter speed is effectively 1/40 second at f/29... If so, the exposure index you found, EI 160, compensates for the exposures you make at the shutter speed and f/stop combination of 1/60 and f/29. This would be a valid interpretation of your test results. I say you have good test process but the test steps you followed lead to results that are valid for that specific shutter speed and f/stop only.

I recommend that you use EI 100 for other f/stop and shutter speed combinations when you develop for 12 minutes. If you develop for less than say, 10 minutes, to pick an arbitrary cutoff, use EI 80.Bill I used neither f/29 nor 1/40 of a second?

konakoa
25-Mar-2014, 10:29
Mario, just re-run the film speed test with a single sheet of film and your meter rated at 160. If you get 0.1 on the densitometer, the test is valid.

For what it's worth, on my medium format Mamiya RZ camera I also rate ISO 100 films at 160.

Kevin J. Kolosky
25-Mar-2014, 10:38
Solid black is Zone 0, not Zone 1.

If you make that correction, the OP's speed works out to be 80, not 160.

- Leigh

solid black is film base plus fog. zone 1 is .10 above film base plus fog. Thus, solid black is zone 0, and zone 1 is .10 above film base plus fog, and is the speed point for a determination of the ISO speed. Basically, zone 1 is about 1/3 of a stop above film base plus fog, although down on the toe the film doesn't behave in a linear fashion. (you'd need calculus to calculate the derivative instead of a linear slope)

closing down from zone 5 (assuming the meter is properly calibrated for a true middle gray and one is using a 10 zone system) for 4 stops is 4, 3, 2, 1. Zone 1.

Leigh
25-Mar-2014, 11:01
No, that's not it, anything you meter becomes Zone V.
Bill,

I'm quite familiar with the way light meters operate, thank you.

My point is that dead black is Zone 0, not Zone 1, regardless of whether you meter it or not.

It's an absolute reference level.

- Leigh

Leigh
25-Mar-2014, 11:11
solid black is film base plus fog. zone 1 is .10 above film base plus fog.
closing down from zone 5 for 4 stops is 4, 3, 2, 1. Zone 1.
Yes, closing down four stops puts you on Zone 1. But you just said solid black is Zone 0.
That's the whole source of the error. You need to stop down 5 stops for solid black.

The main error with this testing procedure is using a black card rather than an 18% gray card (oriented correctly).

The toe on all films is non-linear, but it differs from one film to another.
Using any arbitrary point on the toe as a reference point is invalid. It violates basic rules of metrology.

Meter an 18% gray card and determine what ASA produces a proper Zone 5 density.
That totally eliminates the variability in the toe, which is not a significant component of a print anyway.

Ansel was a musician, not an engineer.

- Leigh

Bill Burk
25-Mar-2014, 13:50
Bill,

I'm quite familiar with the way light meters operate, thank you.

My point is that dead black is Zone 0, not Zone 1, regardless of whether you meter it or not.

It's an absolute reference level.

- Leigh

Sorry if I come across contrary to all your suggestions, I don't mean it that way at all. I meant all my points to be positive responses.

A black card still reflects a couple percent of light and if you expose it according to meter reading it would become gray.
But for a black card to read f/5.6 at 1/60 on a meter calculator dial, the illumination would have to be very bright.
I don't think Mario metered a black card.

I don't think his problem is any mistake between Zone 0 and Zone I because Zone I is the placement where Mario should find 0.10 above Base+Fog.

Mario tested absolute black by developing an unexposed piece of film.

My best hunch right now, is that the shutter is effectively slow in this scenario. It may be a calibrated and accurate shutter according to specifications, but if it is a leaf-shutter design, its speed of operation might span 1/40th of a second, a high percentage of which is fully open at small f/stops such as f/22 2/3 (I called it f/29).

Leigh
25-Mar-2014, 13:58
Shutter speed is always a major source of error.

The specs are 30%, with 50% being a full stop.

- Leigh

Corran
25-Mar-2014, 14:18
I remember you had some issues with the Zone testing last year.

Not to be crass, but why not just shoot some film at an EI of 100 and develop per the manufacturer's recommendation, in N contrast light? That should pretty much get you close, and you can fine-tune.

I did an extensive ZS test a few years ago but at the end of the day it ended up being pretty useless. I did find though that the "common wisdom" of shooting film at half the recommended EI did NOT work for me, and in fact with some combinations I get 2/3 to 1 stop "more" speed than the recommended EI. This is simply due to my metering strategy and certain developers, etc.

After shooting some real subjects you can decide to give the film a bit more exposure, or maybe less, and fine-tune the development time for the highlights. Simply test to find a good EI that gives you enough shadow density for your style and a development time to give you the highlights you desire.

macandal
25-Mar-2014, 14:24
But for a black card to read f/5.6 at 1/60 on a meter calculator dial, the illumination would have to be very bright.
I don't think Mario metered a black card."Meter calculator dial"? Hmm...? I don't know what that is, but if you're referring to a "meter", what I used was a spot meter, Sekonic 358 (?). And no, I did not shoot a black card. It was a grey card, though not an 18% card, it was gray.


My best hunch right now, is that the shutter is effectively slow in this scenario. It may be a calibrated and accurate shutter according to specifications, but if it is a leaf-shutter design, its speed of operation might span 1/40th of a second, a high percentage of which is fully open at small f/stops such as f/22 2/3 (I called it f/29).I used my long lens (fujinon 300mm) because that lens had recently been calibrated. Should I use my 90mm or 180mm lens instead? Should I shoot at a faster or slower shutter speed? If so, can you recommend one?

Thanks.

Bill Burk
25-Mar-2014, 18:26
Shutter speed is always a major source of error.

The specs are 30%, with 50% being a full stop.

- Leigh

I agree 100%!

ic-racer
25-Mar-2014, 18:40
The definition of a Zone 0 exposure is one stop less than the exposure required to produce a density 0.1 log d above film base. Zone 0 may or may not print to d-max on paper.

Taija71A
25-Mar-2014, 19:40
... My results showed that my 'personal' EI for this combination is 160.

... What I used was a spot meter... It was a grey card, though NOT an 18% card, it was gray.

____

'Houston... We have a Problem' (here)...

--
Mario... What is the 'Reflectance' of the Gray Card -- That you used?
Thank-you!
--
Best regards,

-Tim.
_________

Bill Burk
25-Mar-2014, 21:08
... What is the 'Reflectance' of the Gray Card -- That you used?
Thank-you!
--
Best regards,

-Tim.
_________

Well, if it was a reflectance reading that Mario took, it wouldn't much matter.

But... Mario, you didn't take incident meter readings did you?

macandal
25-Mar-2014, 21:14
____
--
Mario... What is the 'Reflectance' of the Gray Card -- That you used?
Thank-you!
--
Best regards,

-Tim.
_________You mean what reading I got from that board I shot? It was f/5.6 at 1/60 of a second.

macandal
25-Mar-2014, 21:15
Well, if it was a reflectance reading that Mario took, it wouldn't much matter.

But... Mario, you didn't take incident meter readings did you?No. I used my spot meter to get a reading from the center of the grey board.

Bill Burk
25-Mar-2014, 22:06
Is there any possibility you metered a flat, non-glaring view of the card... but the camera saw a subject that reflected glare? Just thinking of other ways you might have hit the film with more light than you evaluated.

Taija71A
25-Mar-2014, 22:48
Well, if it was a reflectance reading that Mario took, it wouldn't much matter. But... Mario, you didn't take incident meter readings did you?


No. I used my spot meter to get a reading from the center of the grey board.

>> You mean what reading I got from that board I shot?

____

No.

What is the 'Reflectance' of the Gray Card?
*I have a sneaky suspicion... That it was 'lighter' than 18% Gray...


Quick Answer:

Light Meters are 'Calibrated' to the ANSI/NAPM IT3.302-1994 Standard.

Therefore, if accuracy is of importance to you... And since you are still learning and trying to establish a 'personal' E.I. for your Film/Developer Combination -- I strongly concur with Leigh's recommendation (below):



Meter an 18% Gray Card and 'determine' what ASA produces a 'proper' Zone 5 density.

--
Best regards,

-Tim.
_________

Leigh
26-Mar-2014, 00:46
Without knowing the reflective characteristics of the target and the manner in which it was used, we have
no idea what the proper exposure is.

To elaborate:

The standard 18% gray card must be oriented such that a line perpendicular to its surface bisects the angle
defined by a line from the center of the card to the light source and a line from the center to the light meter.

That's the only condition under which the correct 18% reflectance is realized.
These instructions are included with the Kodak gray card, but absent from some other brands.

Any exposure meter will provide an exposure that would render its target as an 18% gray. However, the
reading depends on an accurate value for the film speed, which is what we're trying to determine here.

Thus we have a totally circular process in which there is no point of calibration or reference.

- Leigh

Mark MacKenzie
26-Mar-2014, 07:29
I have often wondered about the angle of the grey card. Your explanation makes perfect sense. Thank you!

Bill Burk
26-Mar-2014, 07:34
Tim and Leigh,

Knowing the percentage of reflectance and using that in your calculation while determining exposure settings... is important for correctly determining the exposure of a scene when you remove the card prior to taking the photograph.

You might appreciate that in this scenario the percentage of reflectance cancels out, because the card stays in the photograph as you take the shot. The exposure directly relates to what the meter recommended. It's not circular reference, it's a closed loop.

I agree that evenness of lighting and the angle of positioning is absolutely important - the spotmeter can verify that quickly.

Kevin Crisp
26-Mar-2014, 08:17
I appreciate that the original poster is concerned that he has a higher film speed rating than the lower ones most people seem to get and use. I have found with many tests over the years with different film and developer combinations that I also (always) get a result that is at or above the film manufacturer's recommendation. The first time I did a film speed test when I started in LF, I sent the test off to Mr. Picker who read it and told me the 320 with Tri-X was correct. That's double what most people seemed to be using back then. When I started doing my own tests I double checked and got the same result with my Pentax Digital spot meter. Ilford 100 speed film has tested at 175 for me, and that number works.

If you did the test right, that's your number FOR YOUR METER. It's just a number that should work in that personal context for you. If your shutter speeds are bad on the lens you are using that can throw everything off. And if the development time you used turns out to be too much or too little in the development time test, then that can throw off the zone 1 placement a bit. If you take your number out in the field and you're getting empty shadows where you thought there should be some detail, then I'd question your number and whether the test was done right.

macandal
26-Mar-2014, 09:17
As I said before, I did not shoot an 18% gray card. I shot a large piece of gray cardboard (matboard) I had bought from an art store. The surface of the board is not glossy. You've seen matboard, right? Well, that's what I shot. The board was taped to a wall so it was flat facing me. The camera was aimed straight on to the board. I metered the center of the board. When I developed the negatives, I read the center of the board (negative) with the densitometer.

That's what I did.

Jim Noel
26-Mar-2014, 10:24
It is time to stop testing and start making images before you burn out with all these technicalities. Take the Ei and development times which you have determined and see how they work in the real world.

macandal
26-Mar-2014, 16:24
I found this thread (http://photo.net/black-and-white-photo-film-processing-forum/00XIEq) on another board, and this guy got an EI of 200 for Delta 100/DDX. He was, however, testing 35mm film. Like me, though, he too was using a zoom lens. Some people in that thread were questioning his lens selection. I don't know how relevant the use of a zoom lens is in 4x5 testing. I think I'll do my new test with my 180mm.

For what is worth, he was reading his negatives using the same or a similar densitometer as I did (X Rite 810 or 811).

Leigh
26-Mar-2014, 16:32
Like me, though, he too was using a zoom lens.
...
I think I'll do my new test with my 180mm.
Where did you find a zoom lens for 4x5???

Use of a zoom for speed testing can affect the results if the zoom has variable aperture.

- Leigh

macandal
26-Mar-2014, 16:40
Where did you find a zoom lens for 4x5???

Use of a zoom for speed testing can affect the results if the zoom has variable aperture.

- LeighI meant my 300.

Leigh
26-Mar-2014, 16:49
I meant my 300.
Your 300 what???

We could avoid a lot of this back-and-forth if you'd provide complete answers rather than cryptograms.

- Leigh

Corran
26-Mar-2014, 17:01
He means a longer lens, I assume.
A lot of folks (erroneously, of course) call long lenses "zooms" and/or "telephotos" (that one is I guess acceptable in small-format land, where it of course usually is a TP design).

Regardless - if you used your 300mm and focused it on the card, rather than infinity, you may have introduced a bellows factor. That, however, would cause you to get a lower EI due to the loss of light, I would think.

Bill Burk
26-Mar-2014, 20:28
I thought I'd post a graphic representation of Mario's original test.

Notice that the ASA triangle in heavy dashed lines correlates very well with the trend of his data points. That tells me 12 minutes is a good recommended development time.

This doesn't rule out my theory that Mario's 1/60 is actually 1/40.

But I'd like to back down from my theory that smaller f/stops at 1/60 on this lens/shutter work like the shutter speed is slower than when larger f/stops are used.

I'm starting to think that was a red herring in this case.

http://www.beefalobill.com/images/macspeed.jpg

Stephen Benskin
27-Mar-2014, 19:36
A quick look at the graph indicates a good probability that the processing is rather close to Normal.

Isn’t testing error the most likely cause of the EI testing results? We have someone doing a test for the first time. How probable is it that it’s going to be perfect? So perfect, in fact, that it’s possibly to attribute the unexpected results to mechanical camera problems.

The next step should be to retest. Of course from my point of view, it's hard not to suggest the next step should be throwing out the ZS testing methodology when a well known and long established straight forward proper method exists.

Leigh
27-Mar-2014, 20:12
Of course from my point of view, it's hard not to suggest the next step should be throwing out the ZS testing methodology when a well known and long established straight forward proper method exists.
Care to elaborate?

- Leigh

Stephen Benskin
27-Mar-2014, 21:16
Sensitometry.

Leigh
27-Mar-2014, 21:25
Sensitometry.
How about presenting a scenario, at a level of detail comparable to the ZS process already described.

That way readers of this thread can compare the two methods and comment on them.

- Leigh

Bill Burk
27-Mar-2014, 21:30
Expose sheets of film for testing with a sensitometer and process each sheet for a different amount of time. Interpret the results in a similar manner as you would interpret the results of Zone System tests.

Compared to exposing film tests with a camera, using a sensitometer eliminates many possible causes of the unexpected results that we have discussed on this thread (lighting, shutter speeds, f/stop, bellows, lens, flare, meter, test card reflectance and spectral reflectivity), and gets you closer to revealing the characteristics of the film.

Stephen Benskin
29-Mar-2014, 21:42
How many people actually ask themselves what the testing conditions they read about mean and if they are even accurate? The exposure meter places everything at Zone V. Great, but what is Zone V? It can't be a point of density. Films have different shaped curves, and exposure meters are intended to work for negative and positive films. It must be an exposure. Exposure meters are designed to calculate an exposure of 8 / ISO = camera exposure in lux seconds. As the film speed is part of the exposure equation, there must be a relationship between the speed point (point where the film speed is determined) and the metered exposure point, generally referred to as Hg. For reversal film the speed equation is 10 / Hm.

Reversal film speed was once 8 / Hm. That is a change of 1/3 stop. This means that while the method of determining reversal film speeds remained the same, reversal film today is receiving 1/3 stop less light than in the past because the speed equation changed the ratio with the metered exposure point.

Black and white negative ISO film speed is calculated using 0.8 / Hm. That’s 10x or 1.0 logs smaller than the metered exposure of 8 / Hg. In comparison, Zone System testing has the speed point 4 stops below Zone V or 1.20 logs. That’s a difference of 0.20 log-H units.

What this means is that a film, developed to a given point, will produce a different film speed using the Zone System testing method than with the ISO testing method. Ever notice how ZS speeds are almost universally around to 1 stop slower than ISO speeds? Without factoring in the 0.20 log-H difference, a direct comparison between the two speed methods isn’t realistic.

Not only should this bring into question the idea of the accuracy or importance of a "tested" personal film speed; but do to the known difference in exposure between the two methods, Zone System EI’s can pretty much be estimated without testing when developing in a general purpose developer.

Below is the graphed concept for a 125 speed film.

112966

ic-racer
31-Mar-2014, 19:46
One could argue that in the world of B&W large format photography, safety factors in film speed ratings have little adverse consequence and great potential benefit. Especially when one can own perhaps a hundred shutters.

113153

Stephen Benskin
3-Apr-2014, 22:35
One could argue that in the world of B&W large format photography, safety factors in film speed ratings have little adverse consequence and great potential benefit. Especially when one can own perhaps a hundred shutters.
[/ATTACH]

One could argue very successfully because it's true. My concern isn't about the need for greater precision. It's about obtaining a greater understanding of the material and avoiding a false sense of accuracy. What's the point of testing using incorrect theory and wrong scales. In addition Zone System testing yields little information for the effort compared to sensitometric testing.

ic-racer
4-Apr-2014, 04:59
Yes, very good points.

Bill Burk
5-Apr-2014, 08:46
How about presenting a scenario, at a level of detail comparable to the ZS process already described.

Your challenge got me thinking... this really CAN be simplified.

I took your suggestion of a mid-tone test, though I argue it's no good for speed tests. It's great for contrast tests.
With fresh film, I calibrate my sensitometer to the test results anyway.

So I am happy to take the speed as a KNOWN.

For fresh film in standard developer...

1) Make a two-sample "test strip" (take two shots of anything gray - one at meter recommended setting, and one as if bracketing, two stops over).
2) Develop the film for a length of time you wish to test.
3) Measure the density difference between the two resulting negatives, precision 0.1 is good enough, for example one Pentax Spotmeter V needle interval.
-Rule of thumb: A good target is a needle drop of one stop from one negative to the next for a two stop exposure difference. (I'd estimate that as 0.50 CI).

http://beefalobill.com/images/CallingYourShot-Trust.pdf

Leigh
5-Apr-2014, 09:51
Your challenge got me thinking... this really CAN be simplified.
I took your suggestion of a mid-tone test, though I argue it's no good for speed tests. It's great for contrast tests.
Very good, Bill. Looks like a straight-forward process that removes some media variability (i.e. toe shape).

Thank you very much.

- Leigh

Bill Burk
5-Apr-2014, 10:40
Thanks,

I want to add, since it was pointed out in another thread and it relates to ic-racer's chart in post #63.

I don't know if I can fit it into the poem without overcomplicating...

The speed on the box is what you get, for sure. But you choose your relationship with film speed for the quality you want.

In fact I use 2/3 stop less than box speed in many cases as that is MY preferred relationship with film speed.

I test and confirm the rated speed but I use a lower rating in practice.

Stephen Benskin
8-Apr-2014, 18:10
This is an example the ideal Zone System testing scenario using a three quadrant reproduction diagram. It's simply a more analytical and visual way to illustrate the process.

The quadrant in the lower right is the camera image. The subject has an illuminance range of 2.10 logs or 7 stops (Zone I to Zone XIII). The quadrant in the lower left is the film curve. Zone I exposure is placed at 0.10 over fb+f. Zone VIII falls at a density of 1.35 for a density range of 1.25. Exactly how it is described in The Negative.

The quadrant in the upper left is the paper curve. Here a problem arises. The negative density range (NDR) is too large to fit the paper’s log exposure range (LER). The paper has an LER of 1.05 which corresponds to a grade two paper. So instead of Zone I falling at 90% of D-max, it falls in the shoulder of the paper curve. The negative is too contrasty for a grade 2 paper. (Bill and Dale - no helping).

113526

Leigh
8-Apr-2014, 18:27
The subject has an illuminance range of 2.10 logs or 7 stops (Zone I to Zone XIII).
Nice presentation, but a fundamental error.

A subject with a tonality range from ZI to ZIII is eight stops, not seven.
You count the number of zones, not the number of intervals between zones.

I would not expect to capture an eight-stop range on regular film with normal development
printed on #2 paper. That's exactly what your graph shows.

- Leigh

Stephen Benskin
8-Apr-2014, 18:39
Nice presentation, but a fundamental error.

A subject with a tonality range from ZI to ZIII is eight stops, not seven.
You count the number of zones, not the number of intervals between zones.

- Leigh

I have to disagree with you. It is about the intervals. Log 2.10 is 7 stops. Please refer to the data graph in Quad 1 for the reflection density range.

Leigh
8-Apr-2014, 18:53
Stephen, you're missing the point, or more accurately eight points.

There are even eight points in each of your data tables.

If I want to reproduce ZI on a print, that's a point, not an interval.
If I want to reproduce ZVIII on a print, that's a point, not an interval.

If I want eight zones (I to VIII) on the same print, that's eight discrete densities that must be reproduced.
The obvious simplistic example is photographing and printing a step tablet. It has no intervals, only steps.

The distance between the points is measurable, but of no consequence or relevance to the test.

- Leigh

Stephen Benskin
8-Apr-2014, 19:38
This is getting completely off topic. The following example is from Photographic Materials and Processing.

113530

Leigh
8-Apr-2014, 20:29
It seems you don't understand a fundamental concept of measurement, the difference between points and intervals.

This is shown quite clearly on the diagram you just posted.

There are 12 inches in a foot, and 11 intervals.
If you want 12 intervals you must start at zero, not at one. That results in 13 points, not 12.

- Leigh

ic-racer
8-Apr-2014, 20:47
There are 12 inches and 12 intervals but 13 points in a foot.

http://www.catb.org/jargon/html/F/fencepost-error.html

Stephen Benskin
8-Apr-2014, 20:54
First, let's not stoop to insults. That diagram was from what was the first year text book at RIT. According to the accompanying text, "The scene luminance measurements by Jones and Condit that led to the average luminance ratio of 160:1 were made on the darkest and lightest areas of the scene. These areas most nearly correspond to Values I and VIII in the Zone System. This means that the typical outdoor scene contains eight values: I, II, III, IV, V, VI, VII, and VIII. Furthermore, since each value is related to the next by a factor of two (one camera stop), such a scene contains a seven-value range (VIII - I = VII); and the ratio of the extreme values can be found by multiplying 2 times itself seven times (27)."

Another example. This one from Kodak,

113533

Can we begin to discuss the discrepancy between the Zone System NDR and the ISO LER?

Leigh
8-Apr-2014, 22:00
These areas most nearly correspond to Values I and VIII in the Zone System.
This means that the typical outdoor scene contains eight values: I, II, III, IV, V, VI, VII, and VIII.
That's correct.

Eight in my experience is unambiguous.

The point that you fail to understand (or choose to ignore) is that you print levels, not intervals.

If I want a Zone III on a print, I don't want gray between III and IV, or between III and II. I want III.

If I meter a door and want it to be ZV on the print, I don't want something between V and VI, or V and IV.

- Leigh

Stephen Benskin
8-Apr-2014, 22:50
That's correct.

Eight in my experience is unambiguous.

The point that you fail to understand (or choose to ignore) is that you print levels, not intervals.

If I want a Zone III on a print, I don't want gray between III and IV, or between III and II. I want III.

If I meter a door and want it to be ZV on the print, I don't want something between V and VI, or V and IV.

- Leigh

So your argument has changed? It's now an argument from incongruity? The whole concept of the photographic process is about ranges: subject Luminance range, camera image or exposure range, negative density range, and paper log exposure range. The three quadrant reproduction diagram is a graphic depiction of these ranges. In other words, it's the graphic representation of the photographic process.

I've shown a number of referenced examples how it works. The math holds up. My tone reproduction program conforms to theory. I understand.

Once again, why is the Zone System's test negative density range different than what the paper's LER indicates? LER for a grade 2 paper with a diffusion enlarger is around 1.05. Zone System test NDR is 1.25.

Leigh
8-Apr-2014, 23:00
Stephen,

No, my argument has not changed in any respect.

You obviously don't understand the fundamental concept of calibration points versus intervals.
There's nothing I can do to correct that.

Kindly define Zone V in terms of intervals.

- Leigh

Stephen Benskin
8-Apr-2014, 23:42
Stephen,

No, my argument has not changed in any respect.

You obviously don't understand the fundamental concept of calibration points versus intervals.
There's nothing I can do to correct that.

Kindly define Zone V in terms of intervals.

- Leigh

I don't know if you noticed those dotted lines that run through the tone reproduction diagram or the chart with the values of specific points? There are obviously points within the range. I believe you haven't made an attempt to understand the diagram and are jumping to conclusions. I'm assuming you know how to read film and paper curves.

"Kindly define Zone V in terms of intervals."

Beyond the fact that Adams defined Zones as a range, what you have is a straw man argument. The question misrepresents what I am have written and is absurd, but if you want a definition of Zone V, here are a couple of pages I wrote in a thread about the K factor at APUG.

113536 113537 113538

Continued on next post.

BTW Dale, nice link. I never heard of the fence post error.

Stephen Benskin
8-Apr-2014, 23:51
Those pages don't explain what Zone V is in terms of camera exposure, so:

113540 113541 113542

stawastawa
9-Apr-2014, 23:39
I'm not sure where to go with the three graph chart, but I might like it if i know what to do with it. The negative and paper don't match though, so get a different paper (grade 1) and see where things stand.

Taking the chart as someone's 'test' the problem arises in that the user is asking for more results than the test provides. only the zone I exposure/development is tested. Further tests should inform the tester about contrast and they can decide to either develope differently or choose a paper to match.

Why was that paper chosen?

I am glad i decided to read this thread all the way through. I have been meaning to do a nitty gritty series of zone tests and am now curious about finding sensitometry tests that might yield better information.

...

Stephen Benskin
10-Apr-2014, 05:40
I'm not sure where to go with the three graph chart, but I might like it if i know what to do with it. The negative and paper don't match though, so get a different paper (grade 1) and see where things stand.

Taking the chart as someone's 'test' the problem arises in that the user is asking for more results than the test provides. only the zone I exposure/development is tested. Further tests should inform the tester about contrast and they can decide to either develope differently or choose a paper to match.

Why was that paper chosen?

I am glad i decided to read this thread all the way through. I have been meaning to do a nitty gritty series of zone tests and am now curious about finding sensitometry tests that might yield better information.

...

Excellent analysis. The reason why I chose that paper curve is because it had an LER of 1.06 which is close to the center of the range for grade 2. The following chart is from Photographic Materials and Processes. It shows the relationship between negative density range and paper LER.

113573

Leigh
10-Apr-2014, 06:05
The reason why I chose that paper curve is because it had an LER of 1.06 which is close to the center of the range for grade 2.
But you're supposed to choose the paper grade that best matches the density of the negative being printed.

That is not the case in the example you provided.

As you said in post #69:

The quadrant in the upper left is the paper curve. Here a problem arises. The negative density range (NDR) is too large to fit the paper’s log exposure range (LER). The paper has an LER of 1.05 which corresponds to a grade two paper. So instead of Zone I falling at 90% of D-max, it falls in the shoulder of the paper curve. The negative is too contrasty for a grade 2 paper.
So why didn't you choose the correct paper grade for the example?

- Leigh

Stephen Benskin
10-Apr-2014, 07:16
But you're supposed to choose the paper grade that best matches the density of the negative being printed.

That is not the case in the example you provided.

As you said in post #69:

So why didn't you choose the correct paper grade for the example?

- Leigh

That was an example of the Zone System testing conditions. Zone I at 0.10 over fb+f and Zone VIII at 1.35 for a density range of 1.25. According to Adams, this should fit on a grade 2 paper. These numbers come from The Negative. This part of the Zone System test is to determine Normal processing. Normal processing is considered processing for the statistical average set of conditions. How valid is a test if it doesn't accomplish it's stated goals?

One of the problems I've always had with how these numbers was how they are presented in isolation. Even in The Print, Adams never shows the relationship between the NDR and the paper LER. So, what you have with the test numbers is more like doctrine than science. Personally, I don't accept arguments from authority. I want to know why.

What I'm attempting to do with this exercise is to put the Zone System test into context and by presenting it differently, be able to approach it from a different direction for a deeper understanding of the process and hopefully encourage a re-examination of held concepts.

Here's the wrinkle in the example. People have been using 1.25 for the test NDR for decades and most have to have found that their prints based on that test generally print on grade 2. Otherwise it would have been a topic of concern and we would all know about it. So, how do we square that circle? Hint: The 1.25 NDR is the aim for the test.

stawastawa
11-Apr-2014, 00:51
well it would seem there is a problem. Let me run through what has happened with our hypothetical tester:
The tester has gone through and found their personal EI.
This allowed them to match their metering to their development and produce a full scale negative of DR 1.25 from a scene with 8 zones (7 steps).
"Wonderful," the tester thinks as they measures the negative densities. And they go to print the negative.

Then they find that ZI is in the toe, and their Z3 shadow detail is dim and in ZII. To keep it they must do one of the following: dodge, sacrifice highlights, print on a different paper, or make a different negative.

Most choose one of the first three options and adjust from there. After a while they might realise they need to change development to produce a better NDR to match the paper LER. But had the test been set up to find the proper NDR-LER match in the first place the issue would have been avoided.

Now I have a note in my book that 'normal' is ZI @ 0.1 - ZVIII @ 1.15-1.25 , taking the low end of 1.15 gives a DR of 1.05 which would match the LER. i thought i pulled that out of "AA - the print" but it may have been from "the new zone system manual" by uh, white, zacharias & Lorenz i believe.

Stephen Benskin
11-Apr-2014, 19:29
well it would seem there is a problem. Let me run through what has happened with our hypothetical tester:
The tester has gone through and found their personal EI.
This allowed them to match their metering to their development and produce a full scale negative of DR 1.25 from a scene with 8 zones (7 steps).
"Wonderful," the tester thinks as they measures the negative densities. And they go to print the negative.

Then they find that ZI is in the toe, and their Z3 shadow detail is dim and in ZII. To keep it they must do one of the following: dodge, sacrifice highlights, print on a different paper, or make a different negative.

Most choose one of the first three options and adjust from there. After a while they might realise they need to change development to produce a better NDR to match the paper LER. But had the test been set up to find the proper NDR-LER match in the first place the issue would have been avoided.

Now I have a note in my book that 'normal' is ZI @ 0.1 - ZVIII @ 1.15-1.25 , taking the low end of 1.15 gives a DR of 1.05 which would match the LER. i thought i pulled that out of "AA - the print" but it may have been from "the new zone system manual" by uh, white, zacharias & Lorenz i believe.

Your right about the need to individually adjust for varying circumstances, but what I'm using for this example is what can be called the standard model. How the model / system works under average conditions (usually statistically average). The center of a normal distribution curve are the conditions that tend to happen most often. The further from the center, the less likely the occurrence. So, the standard model is an example of the center of the variance. For a statistically average scene, the subject Luminance range is 2.20 logs (7 1/3 stops). Zone System uses 7 stops. Now a 1/3 stop difference isn't very much except when attempting to illustrate how all the variables fit together. The LER for a grade 2 paper printing using a diffusion enlarger is from 0.95 to 1.14. The center of the range is 1.05.

113654

As we are discussing the Zone System standard model, I’ll make a concession and use 2.10 logs for the subject Luminance range. In Appendix 2, Film Test Data, from The Negative, there are a number of examples of film curves. In the first example, the curve labeled “Normal” has a gradient of around 0.58 to 0.61. It’s hard to have a more precise value because the grid lines aren’t detailed. A gradient is determine by rise / run or negative density range / subject luminance range.

Based on Zone System aims, the average gradient for a preferred Normal negative is 1.25/2.10 = 0.59.

The average gradient of the film curve in my example is 0.58. This compares to the example in The Negative. According to the chart on page 220 of The Negative, a normal negative intended to be printed with a diffusion enlarger should have a Zone VIII value of 1.25 to 1.35 (NDR 1.15 to 1.25). A NDR of 1.20 is at the center of the range, but I had a film curve with a gradient of 0.58.

Kodak considers the normal contrast index for a statistically average scene to equal 0.58.

If both methods indicate the same gradient for normal. Why then does Kodak’s (and tone reproduction theory’s) standard model fit on a grade 2 paper with an LER of 1.05 and the Zone System’s standard model doesn’t?

Bill Burk
11-Apr-2014, 20:28
I think Ansel Adams may have shaved a half stop off of Zone VIII

Here's my thinking. I prefer, from experience, a Negative Density Range of 1.05 but the aim in "The Negative" we have been talking about is 1.25. Looking at a graph of "Normal" in his book today, I saw something interesting...

MY aim point for Important Highlight, where I would like my highlight to fall, is right on the lower edge of his Zone VIII

Leigh
11-Apr-2014, 20:33
Then they find that ZI is in the toe, and their Z3 shadow detail is dim and in ZII. To keep it they must do one of the following: dodge, sacrifice highlights, print on a different paper, or make a different negative.
I'm sorry. I don't understand this entire post.

The whole reason they make/made paper in different grades is so you make satisfactory prints from negatives with different contrast ranges.

Why would you consider any other option if success can be achieved by changing paper grades?

- Leigh

Bill Burk
11-Apr-2014, 21:59
Stephen,

I sometimes think we are talking about the missing square puzzle...

http://en.wikipedia.org/wiki/Missing_square_puzzle

Stephen Benskin
12-Apr-2014, 19:29
In testing, it's important to control the variables. When doing a film test, you want to determine the characteristics of the film, so you need to eliminate everything else that can skew the results. In order for the testing results to be applicable to practice, you need to factor back in the variables.

Bill Burk
12-Apr-2014, 21:00
I was looking at one of my sensitometric tests of a 100 speed film which I consider a solid benchmark of film characteristics. At some point of one of the curves the density crosses 0.10, which I deduce corresponds to -2.1 Log MCS exposure. And based on discussions so far, if I were to make a camera test and obtained a similar negative, assuming all is well, the meter using standard calibration would be reading -1.1 Log MCS.

But that's not where Zone System calibration would be. Zone V would be 4 stops from the 0.1 point (which you may recall is at -2.1 Log MCS). Just counting from that point up is -0.9 Log MCS... Two-thirds' stops out to the right. Aside from recalibrating, the obvious way to get the meter to show the shutter speed and f/stop combination that I just used for that negative... would be for me to set the meter to indicate the -1.1 Log MCS... And to do that I would set the meter at Exposure Index 64

So there's 2/3 stop downrating for Zone System right there, which is also 2/3 stop different from Incident reading.

Stephen Benskin
13-Apr-2014, 00:57
Bill, that is basically changing the value of n1 (difference between speed point and metered exposure point) from Δ1.00 log-H to Δ1.20. The attachment has the EI at half the film speed or n1 = Δ1.30 log-H. For a 125 speed film, the metered exposure should be 0.064 lxs.

113687

Bill Burk
13-Apr-2014, 08:10
Right Stephen,

That's what I see happens when you use Zone System metering, to place and "test" for Zone I shadows to be 0.10 density in a low-flare test (stopping down 4 stops from meter reading). This is widely corroborated (that you have to rate film 2/3 to 1 stop less than box speed). Many people who have done Zone System camera tests determine that their system, all variables included, require this 2/3 to 1 stop change from rated speed (change of n-sub-1 from standard calibration Δ1.00 log-H to zone system compatible Δ1.20 or Δ1.30).

So it's apparent to me that 2/3 stop of this change comes from the counting of Zones itself. The distance to the metered point Zone V to the tested Zone I is four stops 1.20

Stephen Benskin
13-Apr-2014, 19:28
As shown in a previous post, the average gradient for Zone System Normal for a diffusion enlarger is 1.25 / 2.1 = 0.59. So what should the gradient be for a NDR of 1.05?

1.05/2.1 = 0.50

Kodak uses a contrast index of 0.58 for aim NDR of 1.05. They also use a subject Luminance range of 2.20. Is that the difference?

1.05/2.20 = 0.48

No. Then how can the Zone System with an aim NDR have an average gradient of 0.59 with is almost identical to a Kodak's CI 0.58 for an aim NDR of 1.05? Obviously something is missing. The equation contains the subject, development, and the resulting negative (to match the print).

If the equation is supposed to represent the results from the variables in the photographic process, what is missing is the camera. Sensitometric testing uses a contacted step tablet to to eliminate the variables of the camera and determine only the characteristics of the film. Those variables need to be factored back in when evaluating how to use the film in shooting conditions.

Even though the Zone System utilizes a camera in testing, the method of testing doesn't represent shooting conditions either.

Bill Burk
13-Apr-2014, 20:43
I'm accustomed to reducing the subject Luminance range by 0.40 to account for flare

This would make 1.05 / ( 2.20 - 0.40 ) which is 0.58

Or I could choose a 2.1 subject Luminance range and then it would become 1.05 / ( 2.10 - 0.40 ) which is 0.62

stawastawa
13-Apr-2014, 22:11
Since the zone system testing tends to set up grey cards or 'evenly lit subjects' to shoot and represent at various levels of gray it is creating an artificial scenario. The test results show film characteristics specific to that situation and style of metering. I'm guessing the zone system methods aren't properly accounting for the subject bright range. But I would think that could be specified to be similar... People do their testing with the idea of a zone IX or zone X for pure whites. Similar to how alternative process users know their medium has a wider contrast range, yes?

The zone system is supposed to take into account the camera and metering style of the individual... you are saying this is not so?

When ever I start thinking seriously about doing some zone system tests I think I had better find a nice contrasty subject with broad surfaces to meter extensively and compare notes after shooting and developing in several different manners. and that time is long over due =)

Leigh
13-Apr-2014, 22:18
Since the zone system testing tends to set up grey cards or 'evenly lit subjects' to shoot and represent at various levels of gray it is creating an artificial scenario. The test results show film characteristics specific to that situation and style of metering.
The film knows and cares absolutely nothing about the subject.

The film's assigned task is to render specific tonal values as specific densities, period.

The concept of an "artificial scenario" is specious. Anything in front of the camera lens is a valid subject.

- Leigh

stawastawa
15-Apr-2014, 21:23
anything is valid, but the zone system tests are setting up a situation, baseline, that will then be used as a guide for shooting a variety of scenarios. Does that guide fit the scenes it is designed to be used for? why is it that both the zone system and kodak have guidelines for shooting, developing and printing on grade 2 paper. ZS uses slightly different shooting and development. why?

(I am now just reiterating Stephen's question)

Leigh
16-Apr-2014, 06:32
The fundamental error is thinking that ZS represents some universal truth.

It does not.

It is an attempt to document the workflow of one particularly successful photographer.

ANY system will provide consistent results if it is calibrated initially, and followed conscientiously.

The problem with ZS, which causes most of the confusion and arguments, is its use of human perception.
Different people see the same scene differently for various reasons, one of which is color blindness.

Almost 50% of the male population suffers from some degree of color blindness.
So surfaces of exactly the same reflectance but of different hues may be seen very differently.

- Leigh

Bill Burk
16-Apr-2014, 07:02
The biggest difference between the Zone System and the standards that give us ASA speeds and time and temperature recommendations...

Is the difference between specifics and averages.

The Zone System is based on metering specific light values that actually exist in a specific photograph and developing as needed for that specific photograph.

While the standards system is based on statistical study of average subjects and developing as needed to satisfy viewers of the best prints that can be made from the average negatives.

The different systems came about approximately the same time, but from ideas of different foundations.

In fact, Leigh is right about there not being 7 Zones. The fact that common practice may deal with 7 Zones is an attempt to reconcile the two different systems. Minor White called N development as the baseline which includes Zones 0 and VIII which you might call 8 or 9 steps or zones depending how you count. The fact it worked is that Minor White had you work from pitch black to pure white on the print.

The idea of working with Zones II to VIII came later and probably part of reconciliation to make Zone System more practical as it evolved.

Leigh
16-Apr-2014, 07:15
I find comments to the effect that a step tablet is not a "real world" subject to be amusing.

Suppose you're shooting step tablets for Stouffer for its ads for step tablets.

There is no such thing as a "phony" subject. Whatever sits in front of the lens is "valid".

- Leigh

Bill Burk
16-Apr-2014, 07:44
Leigh,

Once again, you are right! The difference is not that important. Even if the difference accounted for 2/3 stop, it's consistent. Plus 2/3 stop is not enough to worry about when there are so many other things that are bigger influences on exposure errors. I think it might make a good thread to talk about those.

The issues that may arise from a step tablet are whether they are shot as a photograph from a window-pane, in which case there is flare that keeps toe from properly reaching zero... Or whether it's contacted, in which case the true characteristics of the film are being revealed (with the caveat that the light source had to be a compromise because the necessary science to re-create sunlight in the lab is rather hard to control - I for instance settle for an electronic flash tube, others may prefer a tungsten bulb with an 80B blue filter).

Leigh
16-Apr-2014, 08:48
Hi Bill,

I get around the "artificial sunlight" problem by shooting only b&w. :rolleyes:

Of course, I do use panchromatic (sort of) film. :cool:

- Leigh

Stephen Benskin
16-Apr-2014, 10:46
A change in the suggested color temperature of the light source in sensitometers changed the b&w film speed equation from 1.0 / Hm to 0.80 / Hm or a 1/3 if a stop compensation. I believe the change was from Sunlight to Daylight balance.

Drew Wiley
16-Apr-2014, 11:17
Not all panchromatic films are in fact identical in spectral sensitivity. And spectral sensitivity can even shift at long exposures versus short exp. There are tons of potential variables neither ordinary speed ratings nor the ZS take into account. And one can factor in as many "Zones" to a shot as one damn well pleases. These aren't the laws of physics, just tools meant to be adapted to personal requirements. And you can make any of this either as complicated or a simple as you need. ...

macandal
16-Apr-2014, 13:05
I know that in the age of the internet, posts become part of the public domain. In other words, one no longer owns the post one started. However, I'm going to take some ownership and continue my discussion.

So I moved on to N time testing. After giving it some thought, I decided that my findings (EI 160) for Delta+DDX were correct and proceeded from there.

I shot a real life scene with zones V, III, and VIII in them. I shot this three times (the exact same thing, checking before the exposure to make sure the lighting had not changed: it hadn't). I processed each exposure with an EI of 160 for 12 minutes. I kept all temperatures consistent at 20 C (a degree or two + or -, no more than that). I developed each sheet of film at different times, 100% of the time, 85% of the time, and 115% of the time. However, I did not process a blank sheet of film with each exposure. I simply forgot, so I don't have a reading for fb+fog for each time. Well, except 100%, which, taking my results from my EI testing, is 0.17. Other than that, I don't have any results for 85% or 115%.

Here are my results:

Ilford Delta 100 (EI 160) 4x5 and DDX (1:4)
20 C, 12 minutes, intermittent agitation
Zone V (an actual grey card): f/5.6, 1/8; Zone III (a black backpack): f/2.8, 1/8; Zone VIII (a white wall): f/16, 1/8
I shot all three scenes at f/5.6 for 1/8 of a second (exposing for the gray card).
100% = 12 minutes; 85% = 10 minutes, 12 seconds; 115% = 13 minutes, 48 seconds.




85%
100%
115%


V
0.89
1.05
1.08


III
0.41
0.46
0.46


VIII
1.69
1.96
2.07



Those readings were made using a sensitometer. Oh, and those readings are of the negatives. Of the areas representing zones V, III, and VIII. I remember when I did this testing in a class I took, we read the negatives for the densities, however, now, in the handouts from that class, I can't find what the densities are supposed to be. All I can find are what the densities are supposed to be on a print/enlargement. I also checked The Negative and AA only gives the densities for the print--not the negatives.

I hope I can still use these results even without fb+fog readings.

Thanks.

stawastawa
16-Apr-2014, 14:20
Certainly perception will change how people see a scene. but I think that is irrelevant when discussing the principles of the systems, especially since many exposure is based largely on what the meter reads and the meter is most definitely color blind.

the question remains
Why are the calibration goals of the two systems different?

Leigh, are you suggesting adams' perception was predisposed towards a broader NDR printed on grade 2 paper? if so then it is important to bring that out and lay out a calibration system that does not duplicate that decision, but rather allows individuals to find the 'look' that suits them.


a thought came to me that shooting for a larger NDR gives one more control at the printing stage, and that going to thin results in compressed tonality that can't be easily 'rescued' in the print in some way. I'm not sure I said that very clearly....
I said that maybe adam's liked a broad NDR (1.25) printed on a grade 2 (LER 1.05). perhaps he could see into the shadows, or perhaps he liked to separate shadows more so that he could then dodge and reveal the important ones. I'm wondering if zone system is as it is, not because it seeks to predetermine contrast, but rather because it seeks to have a little extra information spread over the negative. Make sense?

So while kodak wants to get technically good prints by imposing a set dev and print scheme after exposure, the Zone systems continues to play with the image, and final execution and look is determined at printing, where certain details are either sacrificed or skilfully revealed.

I think it could be an answer to the question, but I am sure Stephen has another one in mind.

Leigh
16-Apr-2014, 15:17
Certainly perception will change how people see a scene. but I think that is irrelevant when discussing the principles of the systems, especially since many exposure is based largely on what the meter reads and the meter is most definitely color blind.
Individual perception is absolutely critical to application of the ZS to negative exposure.
It's up to the shooter to place a particular scene feature on a particular zone.
That determination depends on personal factors unrelated to the meters.

The meters and the film emulsion definitely ARE NOT uniformly sensitive over the entire visible spectrum.


Why are the calibration goals of the two systems different?
Why should any two systems agree? If they did, they would merge and there would be only one system.


Leigh, are you suggesting adams' perception was predisposed towards a broader NDR printed on grade 2 paper? if so then it is important to bring that out and lay out a calibration system that does not duplicate that decision, but rather allows individuals to find the 'look' that suits them.
The calibration steps built into the ZS are the factors that "personalize" the system for each individual shooter.
Those steps also eliminate personal errors in use of spot meters, and errors in the meters themselves, which can be rather large. Also, as I've mentioned before, these can compensate somewhat for color blindness of the shooter.

The ZS does not lock anybody into any particular set of values, unless one chooses to be so constrained.
There is sufficient variability built into the system to allow any shooter to tailor it as needed to produce the desired results.

- Leigh

stawastawa
16-Apr-2014, 15:24
Why should any two systems agree? If they did, they would merge and there would be only one system.
- Leigh

I'm not saying they should agree, but it is curious that both systems seek to print on a grade 2 paper and yet choose different NDRs. The reason for why that NDR is recommended should be identifiable.

Stephen Benskin
16-Apr-2014, 15:34
Those readings were made using a sensitometer. Oh, and those readings are of the negatives. Of the areas representing zones V, III, and VIII. I remember when I did this testing in a class I took, we read the negatives for the densities, however, now, in the handouts from that class, I can't find what the densities are supposed to be. All I can find are what the densities are supposed to be on a print/enlargement. I also checked The Negative and AA only gives the densities for the print--not the negatives.


You read the negatives with a densitometer, not a sensitometer. Two very different things. You can find a table of aim densities on page 220 of The Negative. You can also use the curves in Appendix 2 to extrapolate the aim densities.

Why don't you read the edge of the film for the fb+f?

Drew Wiley
16-Apr-2014, 15:39
Gosh. There are all kinds of paper out there too. Just put the damn thing in the enlarger and print it. Get to first base first. Then AFTERWARDS figure out what you
want out of the damn Zone System or whatever. Isn't it ironic how the Zone Systems "starts" at the bottom with Zone III or II for some people. So what's below
that? A black hole? Just depends. Some film have guts down there, some don't. Do you want something there or do you not? Where do you even buy grade 2 paper anymore? If you like to make things harder than they need to be, that's you're privilege. But the key to the Zone System is that you place these zones where you want them to be, both in terms of the light distribution of the scene, and the density of the negative. And it will differ with both the film developer and print paper, and even how you print and develop that paper. As long as you don't overdevelop the neg to unmanageable density. Then if you encounter a scene that doesn't fit your little ''N" pigeonhole, you figure out how to change something to squeeze it in. That is based upon the subject luminance range, how you want the tones to separate and all kinds of things. I've sure done my share of densitometer plotting, but don't think I've ever spent a minute of it regarding the Zone System. There are a lot faster ways to learn that.

macandal
16-Apr-2014, 15:45
You read the negatives with a densitometer, not a sensitometer.Stephen, you are right! I meant to say densitometer. Never used sensitometry in my testing. Of course now I can't edit my post. Moderator: can you please change that word for me? Thanks.


You can find a table of aim densities on page 220 of The Negative. You can also use the curves in Appendix 2 to extrapolate the aim densities.Stephen, I don't have the book in front of me, but, if I remember correctly, I'm pretty sure those densities are for prints. Otherwise, why is he referring to the different readings for the different enlargers one may use (condenser vs diffuser)? As far as using the curves. I wouldn't even know how to do that, and extrapolate--that's one hell of a word, Stephen.


Why don't you read the edge of the film for the fb+f?I didn't think of that. Thanks Stephen.

And thank you for bringing the thread back to its original question.

Leigh
16-Apr-2014, 15:49
... in the handouts from that class, I can't find what the densities are supposed to be. All I can find are what the densities are supposed to be on a print/enlargement.
I also checked The Negative and AA only gives the densities for the print--not the negatives.
That's because the print is all that matters.

There are many factors affecting the translation of negative densities to final print densities, not the least of which being choice of paper and developer. You must tailor the negative to match.

As I've mentioned numerous times, ZS is a SYSTEM, not a chinese menu.
You can't pick and choose items to use or not use.

- Leigh

Bill Burk
16-Apr-2014, 16:01
I'm seeing very steep average gradients here. 12 minutes is not the right time for Mario to develop for Normal. In fact, this explains the Exposure Index of 160 as well. Even I get Exposure Index of 160 when I develop 100 speed film to average gradient of 1.07

tgtaylor
16-Apr-2014, 16:26
As long as you don't overdevelop the neg to unmanageable density.

But if you do, then print it as a salt print.

Thomas

Stephen Benskin
16-Apr-2014, 16:38
Bill, my calculations came out with a slightly lower number, but not significantly. The 85% development came out around 0.82. Something is not right here. Everything seems to the same as the first test and that seemed close to normal processing. The Ilford development chart has 12 minutes for the processing. Unless the developer wasn't diluted, I can't imagine how the processing can be that off for the stated times.

This is actually helping to make my point about how little useful information this type of testing yields. There can be a dozen possible errors, but there's no way to valid the procedures and pin down the problem. How do we know if the stated Luminance range is the actual luminance range tested? My guess is that the luminance range is larger than Δ1.50 log-H. Good testing should limit the number of variables and control the ones that remain.

The OP may not be ready to realize it but what I'm talking about is a part of the point. Accurate information from good testing.

Stephen Benskin
16-Apr-2014, 18:25
It’s impossible for the Zone System testing method and Kodak’s (tone reproduction theory) to have almost identical subject Luminance ranges as well as almost identical gradients for normal development and produce different negative density ranges. You have the same input and the same processing, the output is going to be the same.

Bill has already given the answer away. Between the subject and the film is the camera, and any optical system has flare or more specifically veiling flare. The amount of flare varies depending on a number of conditions, but in general flare produces an overall non-image forming exposure that is added to the camera exposure. The shadows are affected the most with practically no appreciable change in the highlights.

What flare does is to effectively reduce the subject Luminance range as seen by the film. Average flare for an average scene is around 1 to 1 1/3 stops. To calculate the effective illuminance range striking the film, simply subtract the value of flare from the subject Luminance range.

A 7 stop scene Luminance range minus a stop of flare means the film is only seeing a 6 stop illuminance range. (You can see this in the Kodak’s diagram in post #76.) Let’s also use the three quadrant example from earlier. Reduce the range from I to VIII to I to VII and check what happens to the NDR. It’s now 1.06. A one stop value of flare means you are processing for a 6 stop range even though the original subject is 7 stops. While the diagram illustrates the reduced illuminance range that strikes the film, flare accomplishes it differently than shown.

113858

Kodak’s factors in flare to their equation. NDR / (Subject Luminance Range – flare). Kodak uses 1 1/3 stops flare for the statistically average 2.20 Luminance range or

1.05 / (2.20 – 0.40) = 0.58

Leigh
16-Apr-2014, 18:40
It’s impossible for the Zone System testing method and Kodak’s (tone reproduction theory) to have almost identical subject Luminance ranges as well as almost identical gradients for normal development and produce different negative density ranges. You have the same input and the same processing, the output is going to be the same.
Too much book larnin', not enough practical experience.

Have you ever taken any real (non-digital) pictures, and done any processing?

Although the results should be similar, there's absolutely no justification to assume that they would match.

Both systems have huge variables in metering technique and accuracy, and in the selection of film, film developer, paper, paper developer, the tolerances in all those, accuracy of temperature control, agitation method, etc.

All the discussions I've heard/read over the years treat things like film speed and developer activity as though they were absolute inflexible aspects of the process, when in fact nothing could be further from the truth.

- Leigh

Leigh
16-Apr-2014, 20:03
You're just making a cheap ad hominem attack.
You can't argue with my statements, so you attack the person making it.
You've not mentioned the subject of tolerances, as I stated previously:

Both systems have huge variables in metering technique and accuracy, and in the selection of film, film developer, paper, paper developer, the tolerances in all those, accuracy of temperature control, agitation method, etc.

How does that qualify as an ad hominem attack?

The main goal of "personal testing" as advocated for the ZS is to minimize the effect of those variables.

Kodak notes on their datasheets that the values presented are just starting points, subject to adjustment by individual users. They're not cast in stone. They're valid only for processes that exactly match Kodak's.

- Leigh

Bill Burk
16-Apr-2014, 21:17
Both Zone System and the standard system get you to arrive at an f/stop-shutter speed combination for exposure and at a time for development.

No matter how you arrive at the f/stop and shutter speed... for the same shot, if you use the same combination, you make the same exposure... whether your automatic exposure system decided it for you or whether you selected it after careful scene evaluation.

Same happens when you develop... for the same developer and time, you get the same development whether you took that time from a published chart or you calibrated your system for it.

I know it's circular reasoning. I'm just illustrating that different roads to the same settings and development time arrive at the same negative.

Now I believe the standard system is keyed to statistically making you successful, while Zone System enables success by allowing you to call your shots.

rdenney
16-Apr-2014, 21:24
Okay, folks, we're getting complaints. I can't tell who's got the pointy stick and who's being poked by it, so please treat each other with respect or I will delete them all, including the good information they contain. We do not edit posts, we just delete them when they violate the guidelines.

Rick "count to ten" Denney

Leigh
16-Apr-2014, 21:59
Absolutely correct, providing all variables are controlled and remain the same for every exposure/print that's supposed to be identical.

Therein lies the problem. Most of the error terms have not even been discussed, much less controlled.

In fact, the sun's output is not constant.
Obviously it gets brighter and dimmer at any particular location with seasonal changes.
It also varies by up to +/- 3% during the year due to the Earth's elliptical orbit*.

- Leigh

*Source: "The Solar Constant", published by the Australian government, online:
www.ips.gov.au/Category/Educational/The%20Sun%20and%20Solar%20Activity/General%20Info/Solar_Constant.pdf


Both Zone System and the standard system get you to arrive at an f/stop-shutter speed combination for exposure and at a time for development.
No matter how you arrive at the f/stop and shutter speed... for the same shot, if you use the same combination, you make the same exposure... whether your automatic exposure system decided it for you or whether you selected it after careful scene evaluation.
Same happens when you develop... for the same developer and time, you get the same development whether you took that time from a published chart or you calibrated your system for it.
I know it's circular reasoning. I'm just illustrating that different roads to the same settings and development time arrive at the same negative.
Now I believe the standard system is keyed to statistically making you successful, while Zone System enables success by allowing you to call your shots.

Bill Burk
16-Apr-2014, 22:09
It would be great for Mario if we could figure out which of his variables is out of whack. Because something is still wrong. His Zone System development time tests do not give a "Normal" development time.

Right now I see extremely high contrast results. How high is his contrast? I have to develop TMAX100 between 12 and 24 minutes in Stock D-76 to get the kind of contrast he's getting with Ilford Delta 100 speed film in Ilford DD-X at 1:4

Shutter was my first suspicion from day one. But now the development times tests reveal that Mario is getting too much development activity in 12 minutes. This explains the high Exposure Index and it takes some of the doubt away from his shutter.

Mario and I wrote back and forth a couple times. He uses a Nikor tank. That tank takes about 36 ounces of liquid to cover the film. So for 1:4 that would be DD-X 7 ounces concentrate plus 28 ounces water, Mario says that's in a tank with one sheet of film. I have a Nikor tank I haven't used in years. On an old notecard in my cardfile I wrote: "Notes on results. 15% overdeveloped or more. Badly reciprocated (4 minutes) shot came out beautifully others were dense".

So my new suspicion is the Nikor tank's tendency (in my experience) to require less development time than other sheet film development methods. Certainly one sheet in the tank would develop faster than a full load of 12 sheets. My best guess is his "Normal" is about 7 minutes. But with a fully-loaded tank that time might be 9 minutes. And it's just a guess for now.

Leigh
16-Apr-2014, 22:16
So my new suspicion is the Nikor tank's tendency (in my experience) to require less development time than other sheet film development methods. Certainly one sheet in the tank would develop faster than a full load of 12 sheets. My best guess is his "Normal" is about 7 minutes. But with a fully-loaded tank that time might be 9 minutes. And it's just a guess for now.
I gave up on using my Nikor tank for similar reasons, and sold the tank.
I never did more than six sheets because I felt the clearance near the core was too small for 12.

But it still seemed to ? overdevelop ?
I've never had that experience with any other 4x5 processing, so I stopped using the Nikor tank.

- Leigh

Bill Burk
16-Apr-2014, 22:41
If tendency to develop film in less time is the only problem Mario has with the Nikor tank, then THAT can be the outcome of this calibration: a personal development time series that's shorter than most other people report.

My reasons for abandoning it are Fred Picker's newsletters extolling virtue of tray processing (which I totally bought into), some evidence of center band ghost imaging, and the difficulty I have using it because I am missing two parts, the filler cap and the wrapping band.

I suppose since I still have the tank, with a little work I COULD figure out a ratio of processing time differences between Nikor tank and tray...

Leigh
16-Apr-2014, 23:10
I also went to tray development, usually with Diafine.
Very consistent results, up to 6 sheets at a time for 4x5.

- Leigh

Stephen Benskin
18-Apr-2014, 20:34
A flare factor of 2.0 (1 stop) means the value of the shadow exposure has been added to the entire exposure. This effectively doubles the shadow exposure. For a 125 speed film, the statistically average shadow exposure is at 0.0032 lxs. A 2.0 flare factor adds 0.0032 lxs to each step of exposure. The 0.0032 lxs shadow becomes 0.0064 lxs. The metered exposure point of 0.064 lxs becomes 0.0704. The 0.504 lxs highlight exposure becomes 0.510 lxs. The influence goes from 100% in the shadows to 1.3% in the highlights.

The three graphs below illustrate how flare affects the camera image. The example on the left is a non flare camera image from a Δ 2.20 log Luminance range. It’s just like the one in the three quadrant example for the Zone System testing method.

The middle example is of a the camera image with one stop of flare. Flare has increased the shadow exposure effective reducing the subject Luminance range. It’s a common practice in sensitometry to include a non flare curve as reference. Without flare, the shadows fall further down into the film’s toe. Flare hardly makes an impact on the metered exposure point.

The graph on the right shows a camera image with two stops of flare. The effects of flare are more pronounced, further flattening the apparent shadow contrast.

113930

Average flare for a 2.20 log Luminance range is approximately 1 to 1 1/3 stops. Shorter than normal Luminance ranges tend to have less flare and longer than normal Luminance ranges contain more.

The amount and distribution of dark to light areas in the subject also influence the degree of flare. A white square surrounded by a black background has less flare than a black square surrounded by a white background even though they have the same Luminance range.

ISO film speed testing takes flare into consideration even though contacting the film eliminates flare from the test. The average shadow exposure falls approximately Δ 1.30 log-H from the metered exposure point, but the speed point falls only Δ 1.0 log-H from the metered exposure point. A one stop flare factor introduced when shooting added to the shadow exposure will make the difference between the metered exposure point and the film’s speed point Δ 1.0 log-H.

So, even though the film test is without flare, flare is factored into how film speed is calculated. Because without flare, film speed would be at least a stop slower.

The Zone System may use a camera in its testing, but the extremely reduced test Luminance range, a single tonal subject which fills the frame, and keying the exposure at the metered exposure point, produces little to no flare in the Zone System testing method. By stopping down 4 stops from the metered exposure point, the Zone System does not factor in flare when testing. This results in the tester to look for the speed point two-thirds of a stop below where the ISO speed point exists.

This is why Zone System EIs almost universally fall between to 1 stop lower than ISO film speeds.

113933

Bill Burk
18-Apr-2014, 22:19
I agree "that" stopping down 4 stops from Zone V is 2/3 stop different than the distance from the standard metered point and the film's speed point.

I also agree with your assessment that Zone System tests eliminate most flare in the camera tests and do not incorporate flare when applying test results in practice.

But I don't feel those are the reasons "why" there is commonly a one-stop difference. I don't see any connection between standards and Zone System, and the fact they come within 2/3 stop or 1 stop at all, is just coincidence in my mind.

I always thought the committee created 7 2/3 stop subject brightness range by statistical evaluation of many scenes. While the Zone System arrived at subject brightness range by starting with 10 zones, which have 9 stops between them, and further reducing it to 7 stops range by eliminating black and white. This came real close to standards, entirely by coincidence.

One idea that I don't think explains the one stop difference, is the idea that standards eliminated a one stop safety factor but the Zone System included and kept that one stop safety factor to this day. I don't see a one stop safety factor defined in Zone System tests. You aim for Zone I and expect 0.10. No safety factor. Except you fail to incorporate flare, so you get one stop more exposure than you visualized. But failing to account for a factor isn't the same as calling it a safety factor.

The only way I can see standards and Zone System being tied together directly... would be if we can look back further in time and see what the Zone System was based upon, and how it came to the arbitrary 10 Zones (which coincidentally arrive close to standard 7 2/3 stops when you knock out black and white). Photography had at least 50-75 years of people trying to figure out exposure. The Weston meter has it's O and U... maybe it goes back to the meter itself.

p.s. For the original topic... I loaded my Nikor tank with 2 sheets of film, one pictorial and one sensitometric exposure. My normal is 13 minutes 30 seconds in tray to get 0.62 Contrast Index (for TMY-2 in D-76 1:1 at 68-degrees). I am going to give this 9 minutes because I believe that may give me 0.62 Contrast Index in the Nikor tank with the same film and developer... due to the physical differences in agitation and film access to fresh developer in this specific tank compared to sheets in stacks.

Bill Burk
19-Apr-2014, 07:28
My hypothesis about the super-efficiency of the Nikor tank was proved wrong.

I obtained an 0.38 CI in 9 minutes (for TMY-2 in D-76 1:1) in the Nikor tank, and this is practically the same development I get in trays.

Will need to continue working with macandal to find out what the specific issue is that seems to give him very high development rates.

Ken Lee
19-Apr-2014, 09:11
A flare factor of 2.0 (1 stop) means the value of the shadow exposure has been added to the entire exposure. This effectively doubles the shadow exposure. For a 125 speed film, the statistically average shadow exposure is at 0.0032 lxs. A 2.0 flare factor adds 0.0032 lxs to each step of exposure. The 0.0032 lxs shadow becomes 0.0064 lxs. The metered exposure point of 0.064 lxs becomes 0.0704. The 0.504 lxs highlight exposure becomes 0.510 lxs. The influence goes from 100% in the shadows to 1.3% in the highlights.

The three graphs below illustrate how flare affects the camera image. The example on the left is a non flare camera image from a Δ 2.20 log Luminance range. It’s just like the one in the three quadrant example for the Zone System testing method.

The middle example is of a the camera image with one stop of flare. Flare has increased the shadow exposure effective reducing the subject Luminance range. It’s a common practice in sensitometry to include a non flare curve as reference. Without flare, the shadows fall further down into the film’s toe. Flare hardly makes an impact on the metered exposure point.

The graph on the right shows a camera image with two stops of flare. The effects of flare are more pronounced, further flattening the apparent shadow contrast.

113930

Average flare for a 2.20 log Luminance range is approximately 1 to 1 1/3 stops. Shorter than normal Luminance ranges tend to have less flare and longer than normal Luminance ranges contain more.

The amount and distribution of dark to light areas in the subject also influence the degree of flare. A white square surrounded by a black background has less flare than a black square surrounded by a white background even though they have the same Luminance range.

ISO film speed testing takes flare into consideration even though contacting the film eliminates flare from the test. The average shadow exposure falls approximately Δ 1.30 log-H from the metered exposure point, but the speed point falls only Δ 1.0 log-H from the metered exposure point. A one stop flare factor introduced when shooting added to the shadow exposure will make the difference between the metered exposure point and the film’s speed point Δ 1.0 log-H.

So, even though the film test is without flare, flare is factored into how film speed is calculated. Because without flare, film speed would be at least a stop slower.

The Zone System may use a camera in its testing, but the extremely reduced test Luminance range, a single tonal subject which fills the frame, and keying the exposure at the metered exposure point, produces little to no flare in the Zone System testing method. By stopping down 4 stops from the metered exposure point, the Zone System does not factor in flare when testing. This results in the tester to look for the speed point two-thirds of a stop below where the ISO speed point exists.

This is why Zone System EIs almost universally fall between to 1 stop lower than ISO film speeds.

113933

... the Zone System does not factor in flare when testing. This results in the tester to look for the speed point two-thirds of a stop below where the ISO speed point exists.

This is why Zone System EIs almost universally fall between to 1 stop lower than ISO film speeds.

Is that it, in a nutshell ?

Do we know how much flare is introduced by lenses, bellows, camera interiors etc. or is this flare constant attributable to something else ?

sanking
19-Apr-2014, 10:29
... the Zone System does not factor in flare when testing. This results in the tester to look for the speed point two-thirds of a stop below where the ISO speed point exists.

This is why Zone System EIs almost universally fall between to 1 stop lower than ISO film speeds.

Is that it, in a nutshell ?

Do we know how much flare is introduced by lenses, bellows, camera interiors etc. or is this flare constant attributable to something else ?


Ken,

In Beyond the Zone System (starts p. 155 in my third edition) there are procedures for testing for flare. You do have to consider the bellows, lens as well as subject brightness (luminance) range.

Sandy

Stephen Benskin
19-Apr-2014, 10:40
There's more. Doing it a little at a time. I didn't want to the posts to be overwhelming.

Bill Burk
19-Apr-2014, 17:20
Also, while you can and should expose to rise above Base + Fog with expired film, you cannot and should not try to raise up above flare. It moves up with you, so while in Stephen's example the added exposure is 0.0032 lxs, if you try to rise up by doubling your exposure, then the flare will come up too, and it will add 0.0064 lxs everywhere.

stawastawa
19-Apr-2014, 23:00
Also, while you can and should expose to rise above Base + Fog with expired film, you cannot and should not try to raise up above flare. It moves up with you, so while in Stephen's example the added exposure is 0.0032 lxs, if you try to rise up by doubling your exposure, then the flare will come up too, and it will add 0.0064 lxs everywhere.

that makes sense, and gets at my question of how flare factors into how one does / should meter a scene. if you want a zone 1 tone should you just meter for zone 1? flare will raise it a bit but just accept that as zone 1?

well, wait shouldn't you put your zone 1 at zone 0 or zone 1/2 so that flare raises it to 1 while the highlights stay relativly the same? but if you did that the highlights would get less exposure and be flat. so you develope a bit longer to get more contrast?

flat, more contrast? compared to what? normal? but normal is what you test for, and if you test in a way that incorporates flare you shouldn't wont need to think of underexposing and overdeveloping a bit? And underexposing would be the opposite of rating the film as slower = dangerous elimination of safety factor.

sounds like testing should look for flare so you are conscious of when to adjust. Also seems to me that adjustment at the print stage is the way to go, as refinements will likely be made there anyways.

sorry for the ramble, just sharing my processing.

Fredrick
20-Apr-2014, 03:52
I won't go into all the technical details, but I think Bruce Barnbaum explains the filmspeed aspect very well.


http://www.youtube.com/watch?v=rlnt5yFArWo

Bill Burk
20-Apr-2014, 08:40
that makes sense, and gets at my question of how flare factors into how one does / should meter a scene...

All good questions.

You won't get what you expect if you spotmeter a shadow and "expect" it to have a net density of 0.10 on the negative.

But you can understand what to expect and allow flare to work to your advantage...

Darin Boville shared a link recently with a few Ansel Adams videos at the bottom of the page.

https://www.getty.edu/art/exhibitions/focus_ansel_adams

At 2:17 in the second video "Ansel Adams on his working methods." he says "A little camera flare helped the shadow density as expected."

Stephen Benskin
20-Apr-2014, 09:47
I won't go into all the technical details, but I think Bruce Barnbaum explains the filmspeed aspect very well.


That's not film speed. It's exposure.

Rafal Lukawiecki
22-Apr-2014, 04:20
Mario, I've tested the same combination of film and developer, and I have concluded that the recommended time of 12 min would yield contrast higher than N, and also an EI higher than 100. I have since verified my dev times, both in practical use and by running additional, sensitometer-exposed strips, several times, and I stand by them.

I am a little less certain as to the EI, which I think I am slightly underrating, as this film seems faster than it claims, but I'd like to assert that with more science in the future. Still, I am pleased with the actual photographic results I am getting when printing.

At present I use 7m30s for N with EI of 100. 12 min would give me about N+1 and EI approx 125, not far off yours. Please have a look at the curves I posted here: http://www.apug.org/forums/forum37/122474-delta-100-ddx-1-4-film-test-curves.html

For what it is worth, I've also posted a little plotting utility over there, which calculates the dev times. I would welcome everyone, especially Stephen, to comment on that thread, too.

PS. I have just noticed a very interesting comment in the Ilford information sheet for Delta 100: "It should be noted that the exposure index (EI) range recommended for 100 DELTA Professional is based on a practical evaluation of film speed and is not based on foot speed, as is the ISO standard.". See http://www.ilfordphoto.com/Webfiles/201062894918374.pdf

macandal
22-Apr-2014, 09:06
Mario, I've tested the same combination of film and developer, and I have concluded that the recommended time of 12 min would yield contrast higher than N, and also an EI higher than 100. I have since verified my dev times, both in practical use and by running additional, sensitometer-exposed strips, several times, and I stand by them.Rafal, thanks. So, if I were to retest, what would my initial time (starting time) for the stated ASA (100) be?

Again, thanks.

Drew Wiley
22-Apr-2014, 09:13
Flare is never a constant. It varies with the specific lens and bellows extension, type of bellows, orientation of the camera toward the angle of the sun, whether your camera is in the shade or sunlight when you are shooting, how effectively you have shaded the lens, etc. Trying to have a fixed factor for this is nonsense.

Drew Wiley
22-Apr-2014, 09:28
I should clarify that - film tests should always be done in a controlled manner, with minimal flare. Otherwise you have no base reference. Afterwards, in the field,
you can estimate its effect and compensate, just like a filter factor. Best just to avoid it by using a good compendium lens shade.

Rafal Lukawiecki
22-Apr-2014, 09:47
Flare is never a constant. It varies with the specific lens and bellows extension, type of bellows, orientation of the camera toward the angle of the sun, whether your camera is in the shade or sunlight when you are shooting, how effectively you have shaded the lens, etc.

And to complicate it further, flare effect will also depend on the subject. Flare from a uniform, single-tone matt surface that fills the frame (and beyond) will be less noticeable than when photographing a glossy checkerboard of deep blacks and bright whites. Until I started reading Stephen's post, I was pretty much a flare-virgin, which had explained the issues I had with my early film tests, a few years ago.

As Drew says, and as I believe now, it is best to do film tests in a way that eliminates flare as much as possible. To do that, I expose test film sheets using an inexpensive Eseco sensitometer.

Rafal Lukawiecki
22-Apr-2014, 09:55
Rafal, thanks. So, if I were to retest, what would my initial time (starting time) for the stated ASA (100) be?

Again, thanks.

Mario, I wish I could make a good suggestion, but I cannot, since your testing procedure is different from mine. I start by establishing the development time, regardless of EI, then I proceed to establishing EI. This procedure is a simplified adaptation of BZTS test, and is similar to the procedure from Way Beyond Monochrome Ed 2 (WBM). You start by making a few, usually 5, identically exposed test sheets/strips which you develop for progressively longer periods of time, usually a sequence such as 4 min, 5.5 min, 8 min, 11 min, 16 min. Then you use your densitometer to read bars from each strip so that you can find out the curves (contrasts) of each dev time, which lets you decide which is the "normal" one for you. Only then you go ahead to measure the EI, using your newly found normal time.

Having said that, you need to have a ball-park estimate of EI so that you know how to expose the test strips! This should be the manufacturer-provided ISO or nearby. If you are wrong with that, you will end up either with strips that do not start at fb+fog (expose less) or which do not go to high enough densities (expose more).

If you are interested in this approach, you can use the Excel sheet provided by WBM, or my utility which will do the interpolation and find out the N-1, N, and so on times. Read about it here: http://www.apug.org/forums/forum37/122409-algorithm-numerical-approach-computing-ci-contrast-index.html#16 but make sure to use the newer code posted in post #32, which is here: http://www.apug.org/forums/forum37/122409-algorithm-numerical-approach-computing-ci-contrast-index.html#32

In general, some people test EI first, and some, like me, test dev times first, it seems to be a preference.

Leigh
22-Apr-2014, 10:10
Flare is never a constant. ... Trying to have a fixed factor for this is nonsense.
+100

It appears Drew and I agree 100% for once. :cool:

- Leigh

jbenedict
22-Apr-2014, 11:15
There are fifteen pages involved in this discussion. Personally, I think some of you guys are making this much more complicated than it needs to be. What you see with your eyeballs and how much it is what you wanted to do is what should be the result of all types of testing. If it looks good to you, a densitometer measurement won't change your mind. A benefit of sheet film is the ability to expose and develop exposures one by one. Find an evenly lit surface with texture. Meter it and find the exposure to give what you want to have as Zone V. Make one exposure at manufacturer's ISO and one at half that ISO. If you wish, make identical exposures one, two and three stops larger and smaller on the same sheet. Develop both with manufacturer's listed time for the developer of choice. Contact print both on the same sheet of paper for the MTMB amount of time and process for a standard time in a standard developer such as Dektol 1:1 or 1:2. Compare the prints to a standard like a zone scale printed in a book. The one that is closest to Zone V and the scale which looks closest to the printed scale in a book should give you an ISO to start with. Use this initial ISO to expose another series of exposures in the same manner as the ISO test and develop one with the developer and time you used to find the ISO. Develop another one 15% less, another one 20% less and another one 15% more. This should get you in the ballpark for N, N-1, N-2 and N+1. Make comparisons with your printed scale to see if you have done what it is you think you want to do. If it's not close enough for your tastes, try again with different times. Then go out and take pictures. If you want to try two exposure and development pairs, expose two the same and develop one with the time you envisioned when you made the exposure and proof it.(N, N-1, N-2, N+1) If isn't what you were looking for, make the time a little bit shorter or longer.

It is possible to make good photos by using this method to get yourself going. Experience out in the field will refine your techniques and results more than fiddling with measurements and formulas. Change one factor at a time when possible and remember the old maxim: "Expose for shadows, develop for highlights". Once you start getting the results you want using standard procedures then you can try something else to see if you can make pictures you like better. When you are reasonably happy with your method of making your negatives, then you can work on the sophistication of your printing methods. I'm anticipating many disagreeing with me but I'm OK with that. It works for me and works for the dude (who can find lots of buyers for his expensive B&W art photographs) that taught me to do it this way. Trust your eyeballs. If all the calculations make you feel better, go for it. That's my story and I'm sticking to it. ;)

Stephen Benskin
22-Apr-2014, 11:15
I should clarify that - film tests should always be done in a controlled manner, with minimal flare. Otherwise you have no base reference. Afterwards, in the field,
you can estimate its effect and compensate, just like a filter factor. Best just to avoid it by using a good compendium lens shade.

Factoring in average flare is just like normal processing is for the average Luminance range. It puts you into the ball park. Flare is next to impossible to calculate in the field, so you shoot for the middle to limit extremes in variance. Once again, average flare is beneficial to film speed making it about a stop faster than it would otherwise be. It's incorporated into the ISO test. As flare reduces the exposure range, it affects processing. The manufacturer's suggested normal process incorporates between 1 to 1 1/3 stops of flare.

80% of flare comes from the subject. A lens shade helps with the other 20%.

Drew Wiley
22-Apr-2014, 11:38
Have fun in the snow!

jbenedict
22-Apr-2014, 15:19
If you wish, make identical exposures one, two and three stops larger and smaller on the same sheet.

Clarification: I have done this on a single sheet of 8x10 film by pulling out the dark slide in six steps. This would be much easier with roll film. With 4x5, you might be able to put two or three exposures on one sheet or just use separate sheets if you don't want to fiddle too much. Film's getting expensive, though...

Leigh
22-Apr-2014, 15:37
One thing to watch out for if doing full-sheet exposure tests is that the developer recommendations are based on uniform "average" density for the batch of film being developed. Doing a single sheet that's significantly over-exposed can result in developer exhaustion if the amount thereof is close to the minimum required for the film area.

If you develop multiple sheets with some over- and some under-exposed, the average density should avoid this problem.

- Leigh

Ken Lee
22-Apr-2014, 17:20
Ken,

In Beyond the Zone System (starts p. 155 in my third edition) there are procedures for testing for flare. You do have to consider the bellows, lens as well as subject brightness (luminance) range.

Sandy

Thanks, I found the section. It agrees with what has been said here, if I understand correctly.

Having wondered why empirical testing gave a consistent 1-stop difference compared to box-speed, I can now sleep at night :)

Stephen Benskin
22-Apr-2014, 18:24
For what it is worth, I've also posted a little plotting utility over there, which calculates the dev times. I would welcome everyone, especially Stephen, to comment on that thread, too.


Rafal, the design is very clean, clear, and functional with the 0.10 increments. One small observation. The label at the bottom should read Rel Log-H. I am curious where the developmental model came from - 0.40, 0.50, 0.58, 0.70, and 0.88.

Stephen Benskin
22-Apr-2014, 19:18
But I don't feel those are the reasons "why" there is commonly a one-stop difference. I don't see any connection between standards and Zone System, and the fact they come within 2/3 stop or 1 stop at all, is just coincidence in my mind.

Bill, I have to disagree with you. Adams didn't develop the Zone System in a vacuum. He wanted a calibration system that was simple and didn't require a lot of testing equipment. We know that the Weston meter was a critical element in the design of the ZS. We also know that C.E. Kenneth Mees and his team at Kodak (including Jones) were a technical source for Adams. He acknowledges them in the forward of The Negative. There''s no evidence, but I believe he was also influenced by the Munsell Scale. It would have been fairly well known at the time. We also know that ZS EIs conformed closely with the ASA speeds then. Finally, we know that the Zone System testing methodology has remained the same pre and post 1960 film speed standard's revision where film speed doubled.



I always thought the committee created 7 2/3 stop subject brightness range by statistical evaluation of many scenes. While the Zone System arrived at subject brightness range by starting with 10 zones, which have 9 stops between them, and further reducing it to 7 stops range by eliminating black and white. This came real close to standards, entirely by coincidence.

I don't want to get too far into the weeds on this, but the 7 1/3 stop Luminance range doesn't define the whole range. Just like you are attributing to the Zone System, the 7 1/3 stops defines what can be considered the desirable range. What difference does it make if the Luminance is just dim enough that it won't produce any discernible negative density or if it's 10x dimmer. Below the inertia point is below the inertia point no matter how near or how far. Same thing for the specular highlight. Photographic paper can never reproduce it.

114104


There's an excellent example in The Theory of the Photographic Process, 3rd edition. While the film is a transparency, the relevant part to this discussion is below the graph. According to the text, "The nominal shadow point is the point s, which is the deepest shadow in which detail is visible in viewing the scene. To the leftof s is the point, c, cavity shadows. They are deep crevices in tree trunks or between folds in dark clothing, shadows deep in bushes, or other small dark recesses in which no detail is discernible.

The problem of deciding how to define the log luminance range of the scene, for tone-reproduction studies, is usually solved arbitrarily by taking the log luminance interval between the deepest shadow in which detail is visible and the brightest diffuse highlight. Whenever this definition is adopted; however, it should be recognized that important semispecular and specular highlights and probably less important shadows usually lie outside the log luminance range indicated."



One idea that I don't think explains the one stop difference, is the idea that standards eliminated a one stop safety factor but the Zone System included and kept that one stop safety factor to this day. I don't see a one stop safety factor defined in Zone System tests. You aim for Zone I and expect 0.10. No safety factor. Except you fail to incorporate flare, so you get one stop more exposure than you visualized. But failing to account for a factor isn't the same as calling it a safety factor.

I agree that the Zone System never consciously had a safety factor.

Bill Burk
22-Apr-2014, 22:27
Bill, I have to disagree with you. Adams didn't develop the Zone System in a vacuum. He wanted a calibration system that was simple and didn't require a lot of testing equipment. We know that the Weston meter was a critical element in the design of the ZS. We also know that C.E. Kenneth Mees and his team at Kodak (including Jones) were a technical source for Adams. He acknowledges them in the forward of The Negative. There''s no evidence, but I believe he was also influenced by the Munsell Scale. It would have been fairly well known at the time. We also know that ZS EIs conformed closely with the ASA speeds then. Finally, we know that the Zone System testing methodology has remained the same pre and post 1960 film speed standard's revision where film speed doubled.

I agree with all these facts, so it makes it hard for me to still say I think it's a coincidence that Zone System agreed well with old ASA (and thus departed from new ASA by 1 stop). The Weston Meter, certainly played a central role in Zone System. Whatever design that meter encapsulates has a direct impact on the Zone System.

I have to guess that Adams enjoyed his time spent with his technical sources, but whenever they would talk of the averages, Adams would probably bark back he's not talking about averages, he's talking specifics. His issue with the K factor is my evidence of that.


p.s. After testing one of my own shutters, and finding the speed marked 100 is 1/40 second... I can see where macandal may have actually done Zone System testing correctly and arrived at a higher EI than "everybody else" - because Zone System tests include the shutter error. I know we knew that at the beginning of this thread. But now I think more and more that's the root cause here.

Stephen Benskin
24-Apr-2014, 18:57
This example shows how Zone System speed testing works inside the camera; and as using using the speed point is part of the contrast test, how it affects the determination of the highlight density. The find Zone I, the tester determines Zone V by metering a card and stops down four stops. The example uses a full normal range flare and no flare curve as a reference. A single tonal card would only be a point on the curve. Even with a full range subject, the flare at the metered exposure point is very small. A single tonal subject at the metered exposure point would be almost without flare.

Stopping down four stops doesn't move the exposure down into the shadow area of the camera image, but simply decreases the exposure of the entire camera image. This effectively shifts the camera image downward. As you can see, this would place the exposure to the left of the 0.10 over Fb+f film speed point. The speed point falls 1.0 log-H to the left of the metered exposure point. The four stops for Zone System testing places the exposure at Δ1.20 log-H from the metered exposure point. In order for the minus four stop exposure to fall on the speed point, the exposure needs to be adjusted. Generally this is done by changing the EI speed rating from the ISO speed to something around 1/2 to 1 stop slower.

114277

In the standard model of exposure, the 2.20 log luminance range below the metered exposure point would fall a stop below the speed point, at the approximate fractional gradient speed point or minimal useful gradient point, if no flare existed. Factoring in a one stop flare factor, the shadow will fall around the speed point. If average flare of 1 1/4 to 1 1/3 stops was factored in, the shadow exposure will fall slightly above the speed point. Flare effectively increases the speed of the film.

114278

Not only does it increase the film speed, it also reduces the camera exposure range, effectively reducing the scene luminance range by around a stop. In the 3 Quadrant example, the reduction in the Δ log-H from 2.10 to 1.80 makes it possible for a scene with 7 stops to print on a grade 2 paper with an LER of 1.05.

114279

Stephen Benskin
24-Apr-2014, 21:00
The third example in post 155 should be

114286

Bill Burk
24-Apr-2014, 21:02
In another thread, Darin Boville shared a link to some of my favorite Ansel Adams videos. See the bottom of the Getty Museum website:

https://www.getty.edu/art/exhibitions/focus_ansel_adams/

This video in particular, "Ansel Adams: Technique & Working Methods", shows Ansel Adams talking about flare in terms I think we can all understand:

https://www.youtube.com/watch?v=DQT_rzI1Xdw&list=PLij2XTFgmBSSbOx2m3Sfkp20gffaPmPs4

Listen to him at 2:14 as he explains... "A little camera flare helped the shadow density as expected."

Stephen your diagrams are great visualizations and discussion points. I see right away in the third diagram, the Zone System 3-Quadrant diagram... Flare is missing from the "visualization" stage when you use the Zone System.

But even though the Zone System doesn't address it, you can hear Ansel Adams knew flare was going to help the shadow density.

You might think your shadow is going to fall on the film at the speed point, but flare will bring it up. Effectively your Negative Density Range isn't as wide as you imagined.

Bill Burk
24-Apr-2014, 21:10
OK I was referring to your original Zone System 3-Quadrant diagram. Your new Zone System 3-Quadrant diagram illustrates what really happens, while the original diagram illustrates what you think you are going to get. The difference between what you think you'll get and what you actually get, explains why you can aim for a longer negative density range as a Zone System target.... because you are not really going to get what you are aiming for.

Stephen Benskin
24-Apr-2014, 22:03
OK I was referring to your original Zone System 3-Quadrant diagram. Your new Zone System 3-Quadrant diagram illustrates what really happens, while the original diagram illustrates what you think you are going to get. The difference between what you think you'll get and what you actually get, explains why you can aim for a longer negative density range as a Zone System target.... because you are not really going to get what you are aiming for.

Technically that example is more about what happens exposing at the ISO speed rating. I need to put together an example of the 2/3 exposure adjustment plus flare. I have one but not for the same film / paper combination. This example has a CI 0.61 to match the ISO standard's development parameters, but it might do for now. What to look for is how the highlight exposure doesn't change with and without flare and neither does the negative highlight density. Determining the highlight density using using the Zone System testing methodology will tell you nothing about what is going to happen to the negative density range when shooting. A double check to a negative shoot under normal conditions will show the highlight density around the tested aim. It will probably also show a 0.10 density as there will certainly be some shadow area that falls below Zone I and is brought up from the exposure adjustment plus flare. This will reinforce the belief that the negative has a higher negative density range for the seven stop tested range than it is actually getting in practice. The Zone System testing method will produce a good, usable negative. What it doesn't do is properly explain the photographic process.

114288

Bill Burk
24-Apr-2014, 22:42
That's a good diagram. The 2/3 stop adjustment brings the "no-flare" camera test up to 0.10 as expected. Then as Ansel Adams said "A little camera flare helped the shadow density as expected." and this probably brought the Zone II shadow placement to a negative density of 0.40 (that's where one of my Zone II placements fell on a measured example).

So you would NEED to place your highlight density at 1.05 above that, or 1.45, to match the 1.05 LER.

And we haven't introduced yet... enlarger flare.

And we haven't introduced yet the idea that you want to overrun the paper LER a little.

Bill Burk
24-Apr-2014, 22:43
Note... The Zone II is probably 0.40. While the model does try to define Zone I. So 1.45 isn't the aim.

Stephen Benskin
25-Apr-2014, 05:08
And we haven't introduced yet... enlarger flare.

And we haven't introduced yet the idea that you want to overrun the paper LER a little.

Most of my paper curves incorporate flare. Instead of contacting the step tablet, I usually enlarge the test. I don't want to have to add more quadrants.

From a tone reproduction basis, Jones found, “for the soft papers, the density scales of the negative (DR) should in most cases exceed the sensitometric exposure scale of the paper (LER), whereas, for the hard papers, the density scales of the negatives should in most cases be less than the sensitometric exposure scale of the paper (LER).” I've factored in this concept into my developmental model.

Stephen Benskin
26-Apr-2014, 07:17
Bill, we both forgot to mention that speeds derived from using the fixed density point of 0.10 over Fb+f are only accurate for "normal" using the ISO standard's contrast parameters.

Bill Burk
27-Apr-2014, 18:15
True, we didn't get into that.

I take comfort knowing the Delta-X criterion explains that speed doesn't change significantly with changes in development time, when you look at how little the 0.3 Gradient point moves with changes in development time.

And so I understand the speed I find with the ISO contrast parameters, might be OK as the benchmark for that film/developer combination - regardless how long I plan to develop it. Though I still mark my graphs with 0.10 speed points, I appreciate that speed point doesn't have to be 0.10

Stephen Benskin
27-Apr-2014, 21:24
True, we didn't get into that.

I take comfort knowing the Delta-X criterion explains that speed doesn't change significantly with changes in development time, when you look at how little the 0.3 Gradient point moves with changes in development time.

And so I understand the speed I find with the ISO contrast parameters, might be OK as the benchmark for that film/developer combination - regardless how long I plan to develop it. Though I still mark my graphs with 0.10 speed points, I appreciate that speed point doesn't have to be 0.10

I brought up Delta-X as a question of the practicality of doing a speed test for most people. It's unrealistic to expect valid speed results without a sensitometer and proper methodology. The best that can be expected is comparative results between films or developers. I believe time is better spent first understanding what film speed is and isn't, picking an EI that works with your personal shooting and metering style, and focusing the testing instead on contrast determination. The ISO speed is a valid speed that can be used to base a personal EI. A test that doesn't produce a reliable and verifiable result isn't worth doing.

Bill Burk
27-Apr-2014, 22:04
I am with you 100% that the best tests an individual can do successfully with a minimum of effort... is to determine contrast for development times.

Mario can tell us if the film speed tests were helpful... for the purpose of learning.

One thing I learned here was the value of checking shutters (which I always used at nominal speeds before this exercise).

Rafal Lukawiecki
28-Apr-2014, 05:11
I believe time is better spent first understanding what film speed is and isn't, picking an EI that works with your personal shooting and metering style, and focusing the testing instead on contrast determination.

Amen. I came to the same conclusion having dabbled in practical sensitometry over the last three years. The reasoning, for me, is driven by my experience that adjusting small-area, local ("micro") contrast is much harder under the enlarger, than making larger sweeping changes, made easy with VC filtration, while film latitude in exposure tolerance is phenomenal, nowadays, for the films I used, Delta, HP5+ and Tri-X.

All in all, my main use of the film testing/ZS/sensitometry is for the contrast control of the things I cannot (yet?) easily control under the enlarger, even with VC. In practice, it means that I'd no longer indicate N, N+1 etc on the basis of the overall scene range, which I know I can control by other means (VC) but almost always by the localised needs in complex areas of the scene, which I expect would give me grief while dodging, burning, or masking.

EI is almost a secondary concern to me, as long as it is safe enough to have shadow detail on the film.