Testing EI - Neg Dev Time - Print Dev Time

[Alessandro V.]

Hello,

following the discussion about the lack of contrast with the TMAX100 I am doing some test to find out what I might have done wrong and to be more precise in the future.
Looking up in the forum I've landed on this page (http://www.viewcamera.com/pdf/2006/V...%20Started.pdf) and I am trying to follow this test but I am experiencing some problems...

Problem number 1:
When it comes to testing the EI of the particular film the guide suggest to take 6 exposures (by the way why to leave the 6th unexposed!?) rating the film at different speeds (50%, 75%, 100%, 125%, 150% if compared to the declared speed).
For making my life easier I decide to rate the film according to the options of my meter and therefore I have set: 50, 64, 80, 100, 125, 160 ISO.
After I have set up the room for the test I noticed that actually, as I am using one flash as source of light and therefore the only thing that I could change for modifing the exposition is the aperture value, setting the proper f/stop it's absolutely not easy!
As I need to find Zone I I have to stop down 4 stop (therefore multipling by 4 the f/stop that would be suitable for zone V) and these are the numbers that I got:

ISO------Zone V------Zone I
50--------5,6----------22,4
64--------5,63--------22,52
80--------5,67--------22,68
100-------8-----------32
125-------8,03--------32,12
160-------8,07--------32,28

How do you set such f/stop on the lens?!
I have a Schneider Symmar Convertible 150mm/268mm and the f/stop scale it's so tiny that, personally, I think it's impossible to be so precise...

Is there anything I am missing?
Any trick!?

Problem number 2:
This is much easier...
When it comes to take the exposure to find the proper developing time for the negative do I have to rate the film with the EI that I found out from the previous step or the manufacterer one? I think that, logically, it should be the EI that I found out doing the previous test but I wanted to double check with you...


THANK YOU VERY MUCH!

[Heroique]

Is there anything I am missing? Any trick!?

Hi Alessandro,

Can you explain in greater detail why your results are displeasing? And how you produced them? Can you describe the results that would satisfy you?

All I can tell is that your T-max 100 isn’t contrasty enough. (Or is it your prints?)

I appreciate your attention to detail – and determining a personal EI is always a good idea – but a simpler solution might be possible, and it might have little to do w/ your original choice of exposure…

A couple of useful references:

1) Steve Simmons’ Using the View Camera has a clever section titled “Establishing a Personal Exposure Index” – it’s in the “Zone System” chapter.
2) See also John Shaw’s Closeups in Nature and its two excellent sections, “Metering” and “Running a Test.”

[Brian Ellis]

The answer to problem number 2 is to use the EI you came up with in your testing.

As for #1, I've never heard of doing an EI test with flash. Are you sure that your flash isn't automatically adjusting the intensity of the output as you change your film speeds? If it's doing that either through an "automatic" setting or a "TTL" setting then you're defeating the purpose of the test. I almost never use flash so I'm no expert but I'd suggest making the test outdoors or at least in a well-lit room with a single constant light source.

Your goal in testing is to find the film speed that produces a density of a Zone I (not II) exposure, which is .08 to .10 log units above film base plus fog. The 6th unexposed sheet is to give you your film base plus fog reading. But if you're not using a densitomter you don't need to worry about the 6th unexposed sheet.

You don't change apertures to correspond with your meter. You take a meter reading at a particular ISO setting (let's say the manufacturer's speed). An exposure made at any of the various combinations of aperture and shutter given by the meter at that ISO setting would be a Zone V exposures. But you want a Zone I exposure for purposes of the test. So you stop down four stops to get to a Zone I exposure. You make the exposure. Leaving the shutter speed the same you change the ISO setting on the meter to say twice the manufacturer's speed and take another meter reading. The indicated aperture at that shutter speed would produce a Zone V exposure. So you stop down four stops from the indicated aperture for that ISO and make a second exposure. You change the ISO setting on the meter again, to say half the manufacturer's speed. Leaving the shutter speed the same you again stop down four stops to get to a Zone I exposure at that ISO. You make another exposure. You do this until you have five sheets of film, one exposed at the film manufacturer's rated speed and four more at double the speed, half the speed, 75% of the speed, and 25% of the speed.

Use the same shutter speed for each exposure and change only the aperture to get to Zone I. That way you don't have to worry about your shutter being inaccurate at some speeds. Make the first exposure (the one at the manufacturer's ISO) at a shutter speed fast enough to allow you to stop the aperture down four stops for each of the succeeding four exposures without changing the shutter speed.

It's been a while since I did my own testing, you only need to do it once for a particular film and developer and I only use one film and one developer so it isn't something I do every day. If I've made any mistakes here my apologies but I'm sure someone will correct me.

[Alessandro V.]

Thank you all for your responses!

To Heroique...
I have previously opened another topic about the tmax100 and the unpleasant results I had and during the discussion I've learned about these tests for determining the proper EI of film, dev times, etc. I still did not find out where I have made a mistake but I thought that doing a test might be helpful even just for the future and has an experience.

To Brian...
I am shooting with flash because when I will take pictures with my 4x5 I will be in a studio and I'll be shooting with flashes...that's the only reason... :-D
The flash I am using is a Bowen 1000pro, it is fully manual.
Thank you for the explanation, that's exactly what I wanted to do!!!
I mean: keeping the shutter speed always the same (also because using a flash it doesn't matter at all) and modifing the aperture value!
The problem is that I end up with such f/stops, so close to each other, that it seems impossible to set them on the lens!
If you take a look at the kind of table I posted I am sure you will understand what I am trying to say (sorry for my bad english).

Anyway I did not even started with the test because I coulnd't set the f/stop on the lens.

Thank you!

[Oren Grad]

Problem number 1:

...is that your arithmetic is wrong.


As I need to find Zone I I have to stop down 4 stop (therefore multipling by 4 the f/stop that would be suitable for zone V) and these are the numbers that I got:

ISO------Zone V------Zone I
50--------5,6----------22,4
64--------5,63--------22,52
80--------5,67--------22,68
100-------8-----------32
125-------8,03--------32,12
160-------8,07--------32,28


The table should be more like:

ISO------Zone V------Zone I
50--------5,6----------22
64--------6,3---------24,7
80--------7,1---------27,7
100-------8-----------32
125-------9-----------35,9
160-------10,1--------40,3

The last decimal place doesn't matter - you're rounding anyway from a multiplier that's the cube root of the square root of 2; the standard aperture values are themselves approximations.

More importantly, if you've never done this sort of test before, you should start with full-stop intervals, not 1/3 stop. 1/3 stop changes in negative film are very subtle, especially when you don't know what you're looking for. Minor discrepancies in equipment calibration, limited finesse in setting, and minor inconsistencies in the repeatability of your shutter or flash could easily have effects larger than the differences you're trying to observe, thoroughly confusing your analysis of the results.

[Alessandro V.]

Thank you for correcting my math!
Actually I literally followed my meter and I multiplied by 4 the number that I got.

Therefore, supposing I will test the film considering only 1 stop intervals, how many EI should I keep in consideration!?
For example, for a 100 ISO film, should I test for EI 50, 100, 200 or shall I go further with 25 and 400?!

Thank you!

[Bill Burk]

I was going to suggest tests at EI 12, 25, 50 and 100.

But since you still aren't happy with your results, it might be best to test at EI 100 and develop longer and hotter. Work up until you start to get test results that agree with the film's rated speed.

[Oren Grad]

For example, for a 100 ISO film, should I test for EI 50, 100, 200 or shall I go further with 25 and 400?!

I'd go from two stops over to two stops under, or 25 - 50 - 100 - 200 - 400. If you have patience for a sixth sheet, I'd add three stops over, or ISO 12. It may seem like an academic exercise, but if you put in the effort to print all of the negatives, you will learn a whole lot about how B&W film behaves, knowledge that will serve you well even beyond determining a preferred EI for general use.

Good luck! :)

[ic-racer]

In terms of the exposure index test, for simplicity, you can just shoot a single Zone I frame at 1/2 the box ISO. (out door lightning, not flash). If it is 0.1 +/- .03 density then you are done and can move on to the development test.

[Steve Smith]

Being lazy, I used a more simple method!

http://www.freewebs.com/stevesmithphoto/personal.html



Steve.

[E. von Hoegh]

Alessandro, do you have a thermometer yet?

[Alessandro V.]

Hello!

Thank you very much for your response!

I still haven't performed the test as I still need to find the time to go and buy the thermometer, so it would be worthless...

Thank you very much for all the explanation and I'll let you know for sure the results!

[Bill Burk]

Hi Alessandro,

It's good you decided to postpone testing until you get a thermometer.

Running 20 degree C water over my fingers gives me a sensation of coolness with occasional veins of warmth. It's like I feel tiny streams of hot water rippling through that haven't mixed completely with the mainstream of mostly cold water.

I tested how accurate I can be the past few days. I got 24, 20 and 16 degrees C. So without a thermometer my temperature would vary by +/- 4 degrees C. This is "out of control" for black and white processing. I consider variation of +/- 2 degrees C as "under control."

Assuming you can feel for "warmer" and then develop longer, try a negative or two and see if they start looking better. This could give you the confidence to continue.

Other factors could also be working against you:

Bellows extension: Focus at infinity for test shots. When shooting close-up, you need to give more exposure depending on lens-to-film distance.

Flat lighting: "Normal" is a subject with some important parts in shade and other parts in sunlight. In the studio with your one light, everything might be evenly lit. To compensate for flat lighting, develop longer than "Normal". How much longer will be determined by those development time tests that you will do later.

[Kevin J. Kolosky]

Maybe you have a flash meter, but if not and if you are going to be using electronic flash extensively for your work, I would suggest strongly that you purchase a good flash meter. They are of course available new, but you can buy good used ones as well. I have used the Minolta 3, Minolta 4, Minolta 5, and I currently have a Minolta 6. All worked very well for me.

In using black and white film before I had a densitomiter I just made a proper proof and carefully looked at it to determine whether I needed to change the ISO to give either more of less exposure. Remember though that in general, exposure controls the low values, and development controls the high values. So you want to get your low values looking correct by changing your ISO setting, and then, after you get that correct, you want to change your development to control your high values.

The reason I suggest that you use a flash meter is becasue of the Inverse Square Law.
It is much easier to use a flash meter than to figure out the expsosure taking into account the inverse square law. (if you move your lights)

As you will recall, the inverse square law says that light falls off at the square of the change in distance. As an example. if you first have a flash at 10 feet and get a proper exposure at that distance, and then you move the light to 20 feet, you have now doubled the distance, but the light has falled off 4 times (2 squared) or 2 stops, not 1 stop. This concept is very important when using flash, and contrary to what many people think, shutter speed is important when using flash, especially if you have areas that are not being illuminated by the flash. In those cases, you will need to drag the shutter in order to take advantage of the ambient light hitting those areas.

[E. von Hoegh]

Hi Alessandro,

It's good you decided to postpone testing until you get a thermometer.

Running 20 degree C water over my fingers gives me a sensation of coolness with occasional veins of warmth. It's like I feel tiny streams of hot water rippling through that haven't mixed completely with the mainstream of mostly cold water.

I tested how accurate I can be the past few days. I got 24, 20 and 16 degrees C. So without a thermometer my temperature would vary by +/- 4 degrees C. This is "out of control" for black and white processing. I consider variation of +/- 2 degrees C as "under control."

Assuming you can feel for "warmer" and then develop longer, try a negative or two and see if they start looking better. This could give you the confidence to continue.

Other factors could also be working against you:

Bellows extension: Focus at infinity for test shots. When shooting close-up, you need to give more exposure depending on lens-to-film distance.

Flat lighting: "Normal" is a subject with some important parts in shade and other parts in sunlight. In the studio with your one light, everything might be evenly lit. To compensate for flat lighting, develop longer than "Normal". How much longer will be determined by those development time tests that you will do later.

When testing for EI, I'd consider +- 2c (a range of 4c or 7.6f) uacceptable. The idea here is to eliminate all possible variables. Agitation is very important as well. I'd try for +- 1f when making tests in trays, it's no big deal to keep it even closer if you're using tanks.

[Bill Burk]

Right, E. von Hoegh

I meant to illustrate that by feel, temperature would be out of control - and that an expensive, highly accurate thermometer is not required for Black and White processing.

I also confused F and C scales. +/- 1 degree C (or +/- 2 degrees F) are reasonable process control limits for normal everday processing.

But while testing it would be important to work to tighter limits. Write down the exact temperature reading off the thermometer. And while testing it would be good to stay within process control limits of +/- 1 degree F if you can get that level of accuracy.

[E. von Hoegh]

Cool.
Feeling temperature is so subjective as to be useless. Come inside with cold fingers and 45f water will feel warm. As for a thermometer, it just has to be consistent, and most glass tube thermometers are.
I'll grant that I'm a bit fanatical about things, but I just don't see why I should leave any more to chance than neccesary. The making of the photo carries enough uncontrollable variables; I'll control the ones I can. :)

[Don M]

Hi, Alessandro,

This was the old Zone VI (Fred Picker) recommendation, from his Newsletter #46. The procedure was created thru results from the workshops they gave (trying to get decent results from a wide range of participants):

1. In the film speed test, as someone else said, you're looking for a Zone I value that gives you density in the negative of about 0.10 over film base + fog. It's a perceptable value.

2. One aim is to eleminate as many of the variables from your test procedure as possible.

3. Test outdoors. Don't use flash or lights. As Thornton has said, it can be very hard to find a day where there is uniform lighting. So wait for a clear afternoon or a day of constant overcast. (In Vancouver area this past month, this has been a real challenge!)

4. Zone I is dark, so choose a dark, even-toned target placed in even shadow. I used a sheet of black craft cardboard from the local dollar store. If using fabric, watch out for wrinkles. Watch out for weird reflections. Place the target so it won't move in any breeze.

5. Use your best light meter. One camera, on a tripod. One lens.

6. Focus the lens on infinity, because you don't want texture in the image. On a view camera, that means the extension is equal to the focal length (6 inches for a 150mm lens). But it's easiest to simply focus on infinity in the real world and then point your camera to the target. Taking care not to let the focus change when you move the camera.

7. Depending on your preference, you'll be making 5 (my version) or maybe 7 (Picker version) exposures, plus one unexposed sheet (to measure film base + fog). Alternatively, on one sheet, you can pull the dark slide say 1/3 of the way out, though that does create a variation that sticklers will complain about.

8. Be sure the target completely fills the field of view of the lens.

9. Be sure to meter in line with your camera lens. Be careful not to let any shadow from the meter or yourself fall onto the target, or interfere with illumination coming from behind you and reaching the target. Check that the illumination is even across the target (all 4 corners), and adjust if needed.

10. Get ready to move reasonably quickly, to minimize the risk of the light changing or something else going wrong.

11. Set your meter on 1/2 of the manufacturer's film speed (eg, 160 if testing 320 speed film). This is for the 5 shot version. Set it on 1/4 the speed if doing the 8 shot version (eg, 80 for 320 speed film).

12. Take a test meter reading, to see where your exposure series will hit. You will be using only *one* shutter speed, because shutters aren't reliable, particularly in view camera lenses. For the choice of shutter speed, use a mid-range speed, not the bottom or top speeds.

13. You'll be making one-half stop exposures, starting with a wide aperture (eg, 5,6) and moving smaller (eg, 11). Choose the combination that will allow you to change the aperture, while using the same shutter speed for all exposures. You might do a test run, without exposing film, to get familiar with how you'll set the half stop aperture settings.

14. Meter the card for real this time and set your Zone I exposure. Don't take notes during the test. The half stop differences are easy to see in the negatives.

15. Make your first exposure. Then close down 1/2 a stop and make the second exposure. And so on until you've done all 5 sheets (1 stop below, 1/2 stop below, at box, 1/2 stop above, 1 stop above) or 7 sheets (2 stops below to 1 stop above).

16. Develop all negatives, plus the unexposed negative, at the very same time for your usual time and procedure. Development does affect the low values, but not as much as high values.

17. Lay out the processed negatives from darkest to clear. In the ideal world, you find a lab with a densitometer and get them to measure the negs. If two negs are close, choose the one with the slightly higher exposure (you're testing in half stops, but your meter will be set in 1/3 stops, so you can go a little higher or lower).

18. If you have some kind of reflected light spot meter, you can perhaps improvise a relative densitometer reading (this is me, not Picker):

a) tape a big enough piece of plain white paper to a window (even light, and watch the background that it's even), to diffuse the light; this is done better in even shade, not in sunlight; but it needs to be bright enough that the light meter is not hitting at the bottom or top of its indicator

b) tape the clear neg to the paper

c) the other negs probably have enough density difference that you can tell a couple are much too dark, and couple might be about right; choose those negs to tape up on the paper beside the clear neg

d) with a decent light meter, each stop means a difference of 0.3 in density, or 0.1 for each 1/3 stop (we know this because that's how neutral density filters are sold: 0.3 = 1 stop; 0.6 = 2 stops, and so on)

e) you can meter the clear neg to get a base number (eg, EV 8), which is the fb+f density (relative, not absolute)

f) then meter the other negs; this is a little fiddly, as the difference you're looking for is only 1/3 of a stop: eg, 7-2/3 on the EV scale, or just a hair more.

g) If you read all the negs, they serve as a check on each other -- the light meter reading should show a 2 stop total range, whihc is 0.6.

Should be close enough for government work. The sticklers in the crowd won't like it, and will find something more precise. When you shoot your next negs, include one neg at the newly found, tested speed as a Zone I exposure, to make sure you're getting repeatable results. If not, then adjust.