Interesting statement. Any proof?
No matter what Kodak says
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Interesting statement. Any proof?
I was looking at T Max 100 curves, Tmax developer @24°C, publication F32, 1988. They specify the normal developing time is 6.5 min.
The curves show lines at 5, 7, 9, and 11 min, so I interpolated a bit to read a 6.5min time. Doing basic rise over run on the graph, the best I can read it is over a difference of log exposure of 2 (reading from -2 to 0) I get a density rise in that range of 0.3 to 1.9. Doing the math, that gives (1.9-0.3)/(2) which gives a slope of 0.8. Roughly extrapolating the graph back to a 0.58 slope should give a "normal" devloping time of 5 min. I'm also extrapolating that the difference from 5 min to 6.5 min equates to approximately a 2/3 stop push. I realize there is a lot of estimates and approximation here, it's a back of the envelope exercise.
The publications are targeted for the average user. Most of them leave out what they think might confuse people and their charts are too small and lacking detail to effectively use to interpret the data. Resulting in fewer upset people, fewer conspiracy theories, and fewer lawsuits, and sadly fewer informed users.
I couldn't find a copy of F32 1988, but I did find F4016 2018. It didn't specify a Contrast Index value for normal; however, the publication for T-Max Developers J86 did.
The publication for Xtol J109 2018 contained even more information.
What I find interesting is their normal was 0.58 when Dick Dickerson ran the department. Looks like they went back to 0.56 except for films by other manufacturers. Have they fallen so far that they didn't want to retest non Kodak films and just kept the old CI targets the same?
From J109 2000 version:
They also seem to be able to center the values in the cells better in the earlier version.
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There is also a footnote in the Pushing Exposure section of F32 that says (in part): "Pushing exposure results in a slight loss of quality compared with normal exposure and normal processing. You can also use other Kodak developers for pushing these films; however, T Max Developer produces higher quality tone reproduction (better shadow detail) under these conditions."
F32 does specify a CI for T Max 100 of 0.56, and 0.60 for T Max 400.
F32 does specify a CI for T Max 100 of 0.56, and 0.60 for T Max 400.
MattKing
Moderator
What Kodak is saying is that if you under-expose the film by one stop, it will be under-exposed by one stop whether or not you extend development.
If you do extend development in an attemp to compensate for the under-exposure, the shadows will essentially remain unchanged, while the contrast of the mid-tones and highlights will increase.
With under-exposed film, increasing the mid-tone contrast can improve their appearance. Increasing the highlight contrast can worsen their appearance.
The value judgment made (and Kodak's resulting recommendation) is that the increase in quality of how the mid-tones appear is more than offset by the decrease in quality of how the highlights appear.
That judgment reflects knowledge about the subjects most often photographed - often people - and a tendency to make recommendations suited for automatic printing in higher volume processes.
I tend to react more to the mid-tone and highlight rendition in my photographs. For me, the Kodak recommendation works.
If you are more comfortable than I am with less than optimum highlight rendition, you probably should extend the development time.
If you do extend development in an attemp to compensate for the under-exposure, the shadows will essentially remain unchanged, while the contrast of the mid-tones and highlights will increase.
With under-exposed film, increasing the mid-tone contrast can improve their appearance. Increasing the highlight contrast can worsen their appearance.
The value judgment made (and Kodak's resulting recommendation) is that the increase in quality of how the mid-tones appear is more than offset by the decrease in quality of how the highlights appear.
That judgment reflects knowledge about the subjects most often photographed - often people - and a tendency to make recommendations suited for automatic printing in higher volume processes.
I tend to react more to the mid-tone and highlight rendition in my photographs. For me, the Kodak recommendation works.
If you are more comfortable than I am with less than optimum highlight rendition, you probably should extend the development time.
Kodak assumes a photographic subject fitting somewhere in the middle-grey. So, if you underexpose a stop and develop normally, you won't lose detail on the subject. They assume their film is being used for thing-photography and person-photography. Underexposing and normal developing a landscape would be a bad idea. But it really doesn't matter when it's a picture of Aunt Nellie in her rocking chair or the orange Datsun rusting away in the driveway. And Kodak seems to have assumed for the last 20 years or so that everyone is scanning. Scanners do better with negatives that have not been overdeveloped.
I wonder, if that may be because Ilford is British? I always like to think we are the best in terms of bravery, honesty, kindness to our mothers etc
On a more serious note there is just a slight danger that once you introduce ethics into it the actual science involved can get buried
pentaxuser
If I'm reading the text in the data sheet correctly, Kodak is only referring to TMY 400 for the development exception. This makes some sense as the effects of exposure is smaller with long toed curves. Plus they are also suggesting processing to a higher contrast for normal to begin with. What is throwing me, unless I'm mistaken, is that the tables in the data sheet include TMX 100 as a film not to adjust development for a one stop underexposure even though the text suggests otherwise. TMX has a very short toe and exposure changes will me more noticeable.
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I think you are right Stephen about Kodak's statement applying to TMY 400 only. I tried it at 800 and the same development time and it worked very well. While I did not at the same time take the same pics with everything else the same to make a comparison, I have since taken other shots at 400 and the differences to my eye were so marginal as to be non existent. However the key phrase here may be "to my eye"
I suspect that in these kind of matters being discussed here it is what we see or perceive we see that counts
pentaxuser
I suspect that in these kind of matters being discussed here it is what we see or perceive we see that counts
pentaxuser
I've shot Tmax 400 at 800 at either normal or maybe 10% increase in development time in DDX, MCM 100, D76, to my eye there does seem to be a slight loss of shadow detail, otherwise it is my go to film for one stop push. Prior to the return of Tmax 3200 I did on occasion push Tmax to 1600 with does require a 25% to 30% increase in developer time. I agree with MattKing that loss of shadow details is preferable to unprintable highlights. In addition John Carroll in the 1963 edition of The Encyclopedia of Photography wrote that film manufactures often did not publish a films true maximum film speed. Their thinking in 1963 was to provide some leeway for non professional users who did not have access to light meters, better to overexpose rather than underexpose. He then stated that developers that purported to give a particular film an increase in speed were not pushing film but using a film's true speed. (divided developers might have been an exception.) On the other hand most tend to shoot a given film at a slower speed than box speed.
Maybe I need to read through the data sheet again. The discrepancy for me is that the sheet includes TMX in the tables but not in the text.
I had a close look, and there is the push processing chart I included above, plus tables for small tank and rotary push processing that include both 100 and 400 films. The text mentions that TMY can be exposed at 800 with normal development, but the text is silent on push exposure with TMX.
I think the key to this recommendation is the use of T-Max developer. They show a graph of developing time vs contrast for a number of developers. All the other Kodak developers have mostly parallel lines, but the T-Max developer line is much steeper, indicating that it builds contrast much faster than other developers.
I think the key to this recommendation is the use of T-Max developer. They show a graph of developing time vs contrast for a number of developers. All the other Kodak developers have mostly parallel lines, but the T-Max developer line is much steeper, indicating that it builds contrast much faster than other developers.
I stated before that Kodak, Ilford et al never said anything like that. All of the underexpose overdevelop and overexpose underdevelop came from Minor White, Ansel Adams, et al never from the manufacturers. Also the other comments about the manufacturers weasel wording to pimp their sales was not done and they never lowered themselves to those tactics.
Not about TMax 100, no. But the data sheet for TMax 400 is pretty explicit:
There's a similar blurb on the Tri-X 320 sheet.
What they really seem to be saying is if you don't want an increase in grain/contrast, develop normally, and deal with a slight loss of shadow detail. If you don't mind the extra grain/contrast, push away.
And I'm not entirely sure what the argument is about.
There's a similar blurb on the Tri-X 320 sheet.
What they really seem to be saying is if you don't want an increase in grain/contrast, develop normally, and deal with a slight loss of shadow detail. If you don't mind the extra grain/contrast, push away.
And I'm not entirely sure what the argument is about.
Words, of course. If one exposes TMax400 at 800, meters properly, gets the shadow detail one wants/needs, and makes a great print (or whatever media one wants) then the film was not underexposed, but exposed properly. Seems simple to me.
Oh...and a whole bunch of technical stuff.
Wait... You're a retired Kodak engineer? I thought only Ron Mowrey was allowed to be a retired Kodak engineer.
While the Kodak data sheet made a claim that some people might not agree with, it didn't lie. The quote that started this thread came from a response to a statement in another thread. That OP had quote mined the Kodak data sheet. They emphasized the underexposed without extended processing part and didn't mention the caveats Kodak had included. Giving the appearance that Kodak was being dishonest so the OP in the other thread could create a controversy where none existed. It's a particularly unethical debating technique that we are seeing way too often in today's politics. Death panels anyone? Lock Kodak up!
Even if the quote mine was unintentional, I think it should act as an example of how poorly sourced information or rumors can lead to misconceptions and there are far too many of those in photography. That's my argument.
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David Vestal wrote a great piece about this many years ago. Perhaps it was in one of his books. He was of the “lots of exposure, but less development” school. His premise was that manufacturer’s recommendations assumed that we were interested in photographing Caucasians.
Meh… exposure is relative, and what you do is going to depend on what you plan to do with it afterwards. There isn’t really any right or wrong, unless you want to be a purist about it relative to some standard, but even then, that’s subjective. If you’re ok with less shadow detail, then give it less exposure. If you want more shadow detail, then give it more exposure. Same goes for development time and contrast.
of course it is.
A contrast index of 0.55 has always been "standard". It works for me under Rocky Mountain lighting. A CI of 0.65 works better under cloudy (typically European) lighting. If you read the tech sheets, Foma's reliably optimistic ASA ratings are for a CI of 0.6 to 0.7. A difference of 0.02, like between 0.56 and 0.58, is immaterial.
But what you really want to do is go out, shoot a bunch of pictures, print them in the darkroom, and use the ASA and development times that work for you. A CI of 0.5 to 0.55 works for me, except under cloudy skies when 0.6-0.65 works better. But I did those measurements after the fact, and arrived at the development times by experimenting.
The only exception - when I lived in Arcata, on those pea soup foggy summer days at the beach, a CI of 0.8 worked well. Under the redwoods, forget it. The contrast range there, between deep shadows and new green foliage, is much higher than it appears to the eye. I'm sure Vaughn has experienced that.
But what you really want to do is go out, shoot a bunch of pictures, print them in the darkroom, and use the ASA and development times that work for you. A CI of 0.5 to 0.55 works for me, except under cloudy skies when 0.6-0.65 works better. But I did those measurements after the fact, and arrived at the development times by experimenting.
The only exception - when I lived in Arcata, on those pea soup foggy summer days at the beach, a CI of 0.8 worked well. Under the redwoods, forget it. The contrast range there, between deep shadows and new green foliage, is much higher than it appears to the eye. I'm sure Vaughn has experienced that.
Now you've got it. They're not trying to confuse anyone.
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