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DrTang
9-Jun-2017, 09:18
anyone shoot tmax400 at 100 speed? on purpose??


for some reason.. when I first started shooting 5x7, I bought 4 boxes of tmax 400.... which went straight to the freezer as I ended up only shooting 100 asa film.. in studio/ shallow dof and all that

so.. before cracking one open to try various developing schemes with it to see if I like.. is anyone doing this on purpose and if so..do you have any examples??



thanks

peter schrager
9-Jun-2017, 14:39
Why...nothing to gain
Shoot box speed

Fr. Mark
9-Jun-2017, 19:13
Does Tmax 400 transmit UV light well? I think I heard there are serious problems with Tmax 100 that way and I think the OP does a lot of UV required alt printing.

Bill Burk
9-Jun-2017, 19:16
I once did a speed test and (due to vignetting) came up with the insane film speed result of 64. So on the John Muir Trail, I shot it at 64.

http://beefalobill.com/images/redcone_close_spt.jpg

I've never been happier with negatives than I am with those from that trip, the mistake didn't hurt any picture.

Rich14
9-Jun-2017, 19:34
Does Tmax 400 transmit UV light well? I think I heard there are serious problems with Tmax 100 that way and I think the OP does a lot of UV required alt printing.

Tmax 400 transmits UV, unlike Tmax 100 which attenuates it.

Pere Casals
9-Jun-2017, 23:37
anyone shoot tmax400 at 100 speed? on purpose??


for some reason.. when I first started shooting 5x7, I bought 4 boxes of tmax 400.... which went straight to the freezer as I ended up only shooting 100 asa film.. in studio/ shallow dof and all that

so.. before cracking one open to try various developing schemes with it to see if I like.. is anyone doing this on purpose and if so..do you have any examples??



thanks



of course, you do that for N-2 development, a common situation you use that is for very contrasty scenes specially if you are to obtain a darkroom print rather than scanningul

it is also useful to get shadow detail

Just read Beyond the zone system bookgook


What is shooting at iso 100 depends on how you meter. A very skilled phoyographer just knows the density he will obtain in every area of the negative, so BTZS is key information

xkaes
10-Jun-2017, 04:06
Every ISO is different for every film, AND because every film is exposed with different equipment and developed with a different developer with different agitation, dilution, temperature, etc. So before using a new film I determine the correct ISO for the way I expose it and develop it. Usually, I end up exposing film around half of what the box says -- but not always. For example, with AGFAPAN APX 100, I usually shoot it at ISO 20. I was surprised, but that's still 2/3rds of a stop faster than what I normally shoot AGFAPAN APX 25 -- at ISO 12.

I remember several years ago when I was taking a picture by the side of a hiking trail. An obviously 35mm photographer was coming down the trail and asked me what speed film I used in that strange beast. I said ISO 12. She said, "You mean ISO 1200?" I said, "No, ISO 12." I'm sure it took her a while to forget about our encounter!

Pere Casals
10-Jun-2017, 06:54
I remember several years ago when I was taking a picture by the side of a hiking trail. An obviously 35mm photographer was coming down the trail and asked me what speed film I used in that strange beast. I said ISO 12. She said, "You mean ISO 1200?" I said, "No, ISO 12." I'm sure it took her a while to forget about our encounter!


I seen a similar situation, my friends (digital photographers) were surprised and asked me about the ISO of my DIY dry plates. ISO 0.3... When they saw a crop of the image one asked me again... what ISO did you say ? :)

Rich14
10-Jun-2017, 08:01
Every ISO is different for every film . . . I normally shoot AGFAPAN APX 25 -- at ISO 12 . . .


Well, not exactly. The ISO rating for any film is always the same - a sensitometric value the manufacturer determined according to a set of standards established by the International Organization for Standards.

We determine our own personal Exposure Index (EI) for each film based on the characteristics of our equipment and processing variables. If my exposure meter is less sensitive than it should be, if my shutter speeds are not accurate, if I agitate film during processing too fast, my particular EI for a film with an ISO of 100 may be something other than 100. Or it may actually be 100 - all the inaccuracies may cancel each other.

You may rate Tmax 400 at EI 50 and I may rate it at EI 800. But it still has an ISO of 400 in your hands or mine.

/Pedantic Mode :cool:

Rich

xkaes
10-Jun-2017, 11:32
You may rate Tmax 400 at EI 50 and I may rate it at EI 800. But it still has an ISO of 400 in your hands or mine.


Give me a break. The "standards" are not set in concrete, let alone gold. You're caveats, just like mine, prove that, doubly. And the fact that the official, "set in stone standards" have changed over time, and the manufacturer rating of the same film has changed over time, shows that. The "standard" is just a good starting point.

Rich14
10-Jun-2017, 12:09
Ok. Gees. Lighten up. I was just saying that the term ISO as it refers to film speed is an official rating. I wasn't arguing with the concept you described.

But the film still has the same sensitivity the manufacturer said it does whether its in their cameras, in your camera, in mine or in anyone else's. The fact that we assign it a personal sensitivity rating does not change the ISO rating. It just changes the way we have to meter the scenes we photograph due to the way our equipment and methods deviate from the way the manufacturer tested his product and submitted it for its official rating.

And, yeah, the standards are pretty much, um, "set in concrete." No one said any of us have to use the film according to the strict conditions under which the ISO rating is determined. But the manufacturer does.

Peace.

xkaes
10-Jun-2017, 14:02
I'm as light as a feather, but you should not jump to conclusions about things that you are uninformed about. Richard Henry, in his excellent book, "Controls in Black and White Photography" (second edition), spends 10 pages on the history of the changes made to film speed "standards". According to him, the first was set in 1881 by the Committee of the Photographic Club of London. Hurter and Driffield suggested changes in 1890 (hence the H & D curve). There have been numerous changes to "the standard" over time, since then. I will not list them all, or summarize them, here, so as not to rob you of the opportunity to buy and learn from the book yourself.

As in many other fields, "standards" change over time, sometimes very quickly and radically. The CPR "standard" resuscitation method has changed three times from what it was when I learned it just a few years ago. The few lawyers, who can somehow keep up with the ever-changing "standard of care" of medical problems and procedures can make a fortune. Standards are ALWAYS "at THIS point in time" -- not set in concrete.

As to a film speed "standard", Henry concludes that it "can be, and should be where possible, determined by the individual photographer."

165971

Bill Burk
10-Jun-2017, 15:15
ASA/ISO film speed ratings and exposure index (EI) are interpretations of the film's characteristic curve distilled down to one number (for ASA/ISO the rest of the story is spelled out. When you do things your own way, it helps others a lot when you tell the rest of your story).

The curve could be graphically represented as a line. Before you develop the film, this line could potentially be of the lines shown on my graph, with possibilities that vary above, below or in-between... But aside from some crazy MacGyver schemes you'll never get a usable density on this film with any amount of light less than about -2.9 log MCS. So please try to put more light on it than that.

Of course after you develop the film it will result in one curve. (You could reduce or intensify to change it later if you like but generally you stay with the line you get).

http://beefalobill.com/imgs/Sept9TMY2.pdf

The film characteristics are what they are. The development you give the film is what it is. And the density you get on that film (developed that way) for the amount of light you put on it... is not going to change.

You could print this graph out and rely upon it. Play with the interpretation. Print a few copies out and pencil in your own lines over the top of this graph... Draw a vertical line at "100" on my Film Speed scale at the top. Under that 100 is where your shadows (very roughly) might fall. Then draw a line down at "10" (ten times the light). That's where your meter reading will fall (think Zone V). Draw a line down under the 0.0, that's roughly (again very roughly - I'm just trying to give you an idea not being scientifically accurate) where your highlights will fall... when you decide to shoot at 100.

Try several interpretations. I personally use 250 these days, and develop to a contrast between 0.5 and 0.6 (10 to 14 minutes for me) but sometimes I go back to 400, develop for 13 1/2 minutes and do my best to keep anything I want detail in above that minimum amount of light that does any good... "-2.9 log MCS".

As I said the EI is an interpretation of the characteristics. If you draw lines over the top of my graph, that's fine, there are infinite interpretations that can be made... your interpretation will help you arrive at an exposure that gives you the kind of negatives you like.

But the curves themselves will not change, the characteristics are what they are.

How much light you decide to put on the film is what changes.

Rich14
10-Jun-2017, 15:37
I'm as light as a feather, but you should not jump to conclusions about things that you are uninformed about. Richard Henry, in his excellent book, "Controls in Black and White Photography" (second edition), spends 10 pages on the history of the changes made to film speed "standards". According to him, the first was set in 1881 by the Committee of the Photographic Club of London. Hurter and Driffield suggested changes in 1890 (hence the H & D curve). There have been numerous changes to "the standard" over time, since then. I will not list them all, or summarize them, here, so as not to rob you of the opportunity to buy and learn from the book yourself.

As in many other fields, "standards" change over time, sometimes very quickly and radically. The CPR "standard" resuscitation method has changed three times from what it was when I learned it just a few years ago. The few lawyers, who can somehow keep up with the ever-changing "standard of care" of medical problems and procedures can make a fortune. Standards are ALWAYS "at THIS point in time" -- not set in concrete.

As to a film speed "standard", Henry concludes that it "can be, and should be where possible, determined by the individual photographer."

165971

Whether or not standards change over time has nothing to do with the difference between a published value for a material that has been determined by the prevailing set of standards and a personal value that applies only to one's own equipment and working methods. Obviously, you do not grasp the concept.

No, when one determines a working Exposure Index that is not a new and personal ISO value. It's a personal Exposure Index. It doesn't really matter what it's called if it works for the individual photographer, but the name of the value is different. You have become very offended that I have made an issue. I underestimated the thickness of your skin. Sorry about that. My first post was a light-hearted attempt to point out that I was being overly specific. I joked about being pedantic, and I thought you would take it in that way, but this has gone downhill from there. You're just like a dog with a bone. You can quote whomever you wish. You're not understanding the issue at all.

I'm done. Continue to worry your bone as much as you'd like.

Pere Casals
10-Jun-2017, 15:59
Ok. Gees. Lighten up. I was just saying that the term ISO as it refers to film speed is an official rating. I wasn't arguing with the concept you described.

But the film still has the same sensitivity the manufacturer said it does whether its in their cameras, in your camera, in mine or in anyone else's. The fact that we assign it a personal sensitivity rating does not change the ISO rating. It just changes the way we have to meter the scenes we photograph due to the way our equipment and methods deviate from the way the manufacturer tested his product and submitted it for its official rating.

And, yeah, the standards are pretty much, um, "set in concrete." No one said any of us have to use the film according to the strict conditions under which the ISO rating is determined. But the manufacturer does.

Peace.


Well, the film speed is not officially calculated in strict conditions, in the sense manufacturer can use any developer to measure film speed. Active ISO norm says that, so manufacturer can use a developer with speed loss, a developer of the D-76 kind, or a developer that increases speed. In fact manufacturer should say the developer he used for speed calculation.

Once developer is selected... yes, there is a very strict way to calculate speed.

Normally box speed is calculated by using a developer of the D-76 kind, but this is not mandatory, an obvious example is ADOX CMS 20.

So (IMHO) at the end practical speed depends a bit on the developer we use, and a lot on how we meter.

Bill Burk
10-Jun-2017, 16:45
I think everyone here gets it....

You can get a real speed less than or more than the ISO by changing developer. It typically won't be much different, but when you use a different developer of course you will need to test at least to know the speed. I would test for the characteristic curve family.

I think of the notion of "speed" as an overlay to the characteristic curves. That's why I print out a copy of the graph and draw "what if" pencil lines when I want to try something unusual and new. I'll often draw actual density points on the same graph to understand how well I hit my aim.

xkaes
10-Jun-2017, 17:15
Well put, Bill. As Henry would probably say, chances are the only thing that you will have in common with the way that ISO determines the film's speed, will be the film itself. So, assuming that you can, you need to figure out speed yourself -- using the manufacturers "unknown standard" as a jumping off point.

165972

Jac@stafford.net
10-Jun-2017, 17:42
It is likely that you do not know the exposures of your film. Exposures can diverge as much as two stops or greater due to inaccurate shutter speeds which are common in LF. That, plus errors in metering and processing should concern the photographer.

If all we had to worry about was a two-stop error but with accuracy in all of our other practices correct, we would be blessed.
.

Pere Casals
11-Jun-2017, 03:11
It is likely that you do not know the exposures of your film. Exposures can diverge as much as two stops or greater due to inaccurate shutter speeds which are common in LF. That, plus errors in metering and processing should concern the photographer.

If all we had to worry about was a two-stop error but with accuracy in all of our other practices correct, we would be blessed.
.

I agree completely with you, one cannot say that rating film speed 1/3 stop more or less makes wonders, while not checking speed of own shutters.

Even a brand new LF shutter usually had an specified tolerance of +/- 30%, so for 1/60 it can shot 1/40 or 1/80, and this is a full stop difference. One marked speed can be a bit higher and the next one can be the same speed, and still the shutter will be in specs.

With negative film... overexposing a bit just works as a safety belt, but for slides (IMHO) it is really necessary to have a shutter tester to know real speeds and consistency of every marked speed of every shutter. Not that complicated or expensive... and it really helps.


Regards

DrTang
11-Jun-2017, 16:16
there is no shutter speed issues or metering issues.. I shoot with strobes in a studio and meter with an incident flash meter with the dome facing the camera lens right where the model is

so

400 at 100 - - does not seem worth the hassle and maybe I'll sell off the film and buy more FP-4

Pere Casals
11-Jun-2017, 16:25
there is no shutter speed issues or metering issues.. I shoot with strobes in a studio and meter with an incident flash meter with the dome facing the camera lens right where the model is

so

400 at 100 - - does not seem worth the hassle and maybe I'll sell off the film and buy more FP-4


IMHO there are 2 different things that can make a difference TMY vs FP4.

One is spectral response, how face colors are separated in the color to BW conversion film makes, this can be matched by filtration, but sure we need some filtration to make a film look like the other.

The other thing is how skin glares are depicted, this is important, IMHO

None of the two films is better than the other, but different filtration/processing if needed to look similar...