T Max 100 vs T Max 400 development times

Does anyone out there find that the 100 requires slightly more (+10% or so) development time than for the 400? This perplexes me, as slower film usually requires less development.

I have found this, repeatedly, to be the case. I am using fresh film, same developer (both clips developed in same tank), controlled lighting. The determination factors for me here are: identical contrast yielding the same shadow detail. - David Lyga

Good Morning, David,

Optimal "normal" times are slightly different. I use 10 minutes for T-100 and 9 minutes for T-400, both in T-Max developer diluted 1:7 directly from concentrate. With times so close, however, I wouldn't hesitate to process both films together in the same tank for, say, 9.5 minutes, assuming a non-critical situation. With roll film or 35mm, the reel with T-400 film can be put on top in the tank and pulled a minute ahead of any T-100 and dropped in the film washer while the T-100 continues development for another minute. Most of the time, I will slightly adjust the time for either film depending on the subject contrast.

Konical

But the fact is that you just confirmed my suspicions and for that I thank you. 'Development tables' are one of the most frustrating factors in analog photography. They ALL state that 100 should be processed LESS than 400. That seems to be the 'necessary' thing to say even if, in the real world, that is not the case.

Usually the slower the film, the less development needed to attain adequate contrast. There was another exception that I remember: Panatomic X which required considerably more development time than Ilford's Pan F does. There simply is no set formula here and each film type must be determined privately because development tables apparently are not all that accurate (or even in agreement with each other's).

Of course, it must be said, with emphasis, that exposure plays a part in the final contrast as well, and this exposure must be accurate in order to be able to compare film development times with the prospect of attaining consistent results. My exposures were exactly two stops apart and conform to the box speeds (which are accurate for these two films.)

Again, Konical, the difference is sufficiently trivial to 'make up' for the difference with enlarger filtration. But that difference goes the WAY that I thought I was experiencing and that is significant to me. - David Lyga

David Lyga said:

But the fact is that you just confirmed my suspicions and for that I thank you. 'Development tables' are one of the most frustrating factors in analog photography.

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You can certainly throw out the impersonal development tables if you use a sensitometer to expose test strips and graph the results... It is very nice to go to the notebooks and see a graph that "fits the ASA triangle" and know that, for that film 11 minutes is "normal".... for me. And once you have a family of curves, you can go from there. Even if you didn't do Zone System notes, you can remember the roll was shot on a foggy day so check the graphs to find which one would "expand" one stop more as if N+1.

David Lyga said:

There was another exception that I remember: Panatomic X which required considerably more development time than Ilford's Pan F does.

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Love the smell of Panatomic-X, couple days ago I took in a deep savoring sniff from the paper backing...

Also, it only needs 4 minutes in the fix.

Shoot fuji, the acros 100 in 35 AND 120, the neopan 400 and the 1600 all use the same exact time and can be developed in the same tank.

Strange that tmax 100 need more time as it can be pushed to 200 without changing anything (or so Kodak claims anyway)

A good opportunity to consolidate to using one film. Tmax400 is pretty handy. For big enlargement smoothness and less magnification, I've preferred going up in film size to a MF/LF rather than massively enlarging 35mm tmx even though it has fine grain.

There really isn't any strong connection between the development times of two different films, unless they have been designed to be so connected by their manufacturer.

There is a lot of difference between the two films, so it doesn't surprise me that the development times do not follow the pattern observed in other films.

And as for Kodak's recommendation for dealing with one stop of under-exposure for either T-Max 100 or T-Max 400 (no increase of development time) that is merely a reflection of the fact that Kodak has determined that the inherent latitude of the films means that the loss of shadow contrast resulting from one stop under-exposure is less of a problem then the loss of highlight detail and contrast that results from increasing the development time. It goes without saying that increasing the development time doesn't create shadow detail that isn't there.

Thanks all.

MattKing, I was careful to not allow highlight blocking through over development but your point is well made about Kodak's reasoning. However, I would refute Kodak in that a one stop underexposure does (slightly) affect contrast and I would therefore increase development time for the underexposed film by maybe 5%. Rather trivial adjustment but theoretically sound. - David Lyga

Just a thought David, while I do agree that the total density will be lower with less exposure, that doesn't necessarily mean a change to the film curve is needed.

I think what Kodak is essentially saying is that for typical use either EI 400 or 800 there will normally be plenty of info to make virtually identical prints of typical scenes.

Yes, surely for high contrast scenes or tightly spot metered work, there very well could be impacts on the print but for most people it won't normally matter.

markbarendt said:

Just a thought David, while I do agree that the total density will be lower with less exposure, that doesn't necessarily mean a change to the film curve is needed.

I think what Kodak is essentially saying is that for typical use either EI 400 or 800 there will normally be plenty of info to make virtually identical prints of typical scenes.

Yes, surely for high contrast scenes or tightly spot metered work, there very well could be impacts on the print but for most people it won't normally matter.

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And Mark Barendt recently demonstrated that in this test, where the result showed considerable latitude in Exposure Index - where all the shots fell on the straight line - so they all printed on the same grade and all looked the same.

(there was a url link here which no longer exists)

Of course the latitude is really only to overexposure. Once something is off the bottom it is gone, though it may not be an issue for a particular picture that doesn't have important shadow detail that far down.

I do understand Kodak's pushing recommendation and it makes sense since increasing the development time doesn't recover the lost shadow detail.

Mark Crabtree said:

Of course the latitude is really only to overexposure. Once something is off the bottom it is gone, though it may not be an issue for a particular picture that doesn't have important shadow detail that far down.

I do understand Kodak's pushing recommendation and it makes sense since increasing the development time doesn't recover the lost shadow detail.

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Actually Mark there can be room both under and over, it fully depends on the scene and metering techniques.

This morning I extended the test Bill linked to above (indirectly, same dog but different lighting/scene) with a shot at the tail of another roll.

That shot proved for me, for Delta 400 in DD-X at least, the point you make in your last sentence. I got nice detail where I wanted it from a frame incident metered and shot at 1600 but developed for EI 500. I'm going to try a frame or two shot at 3200 and developed at 500 on the next roll.

The camera meter though, center weighted and matrix, in my F5 was being seriously fooled by the white background telling me I'd be 2-stops over exposed, had I followed the camera's lead the shot would have lost the detail I wanted. (Good spot metering and zoning techniques would have worked fine too, they would simply have taken a bit more thought.)

Well, the straight line assumes that ALL is within that straight line. I believe that at box speed that is on the cusp and that any further reduction in exposure BEGINS (not necessarily perceptive to most) to reduce the shadow detail's presence on that straight line. I would begin to give ever so slightly more development with an EI 200 for TMX.

David I'll definately grant that the application of these principles needs to fit the individual user and that as exposure is reduced there is less and less latitude at the shadow end of the scale.

One point I'm trying to make though is that normally I don't print clear to the toe. I don't think I'm odd in this respect either. Yes, a certain number of us shoot tight enough to the toe or long enough scale subjects that a small change in EI might really matter. It is obvious from my tests that I'm not in that group.

A second point that I want to make, and that Mark Crabtree also made above, is basically summed up in the old axiom "expose for the shadows and develop for the highlights"; development changes have very little effect on film sensitivity and shadow detail; it's almost all about the exposure when we are placing subject matter down close to the toe. Changing your development from 100 style to 200 style is about fitting the scene to the paper not getting more shadow detail.

Mark Crabtree said:

Of course the latitude is really only to overexposure. Once something is off the bottom it is gone, though it may not be an issue for a particular picture that doesn't have important shadow detail that far down.

I do understand Kodak's pushing recommendation and it makes sense since increasing the development time doesn't recover the lost shadow detail.

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As the subject brightness range increases (i.e., more of the gray scale is used at both ends), the film's latitude for any exposure error decreases. Information on the negative can be lost at either end of the gray scale with too much error in the chosen exposure.

David Lyga said:

Does anyone out there find that the 100 requires slightly more (+10% or so) development time than for the 400? This perplexes me, as slower film usually requires less development.

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I develop the tmax 100 and 400 in xtol. At a 1+1 dillution the tmx need 11 minutes, the tmy2 9,5 minutes. So the 100 requires more time for the same beta.

Joerg Bergs said:

I develop the tmax 100 and 400 in xtol. At a 1+1 dillution the tmx need 11 minutes, the tmy2 9,5 minutes. So the 100 requires more time for the same beta.

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I like TMX, but don't use either that or TMY much any more. When I did use them I found the same thing. It is not all that likely that Kodak made a mistake on this. There were some erroneous times given, but not usually on something as basic as this.

I think it is more likely that the very different highlight contrast of the two films is the reason. I shoot a fair bit in full sun and in available indoor light. In those sorts of high contrast situations I think the very slight tapering of the highlights with TMX compared to the straight line (or sometimes slightly upswept) highlight curve with TMY means you can give more development with TMX (or need to give less with TMY, depending on how you want to look at it).

my results, your may be different