Dynamic range of TMax

Discussion in 'Black and White' started by stevecolemanaus, Feb 21, 2009.

  1. Can anyone tell me the In-Camera Dynamic Range for Kodak TMax. By this i mean the in-camera exposure latitude from detailed dark areas to detailed highlights.
    Many thanks in advance for your help... :) S
  2. I read years ago that Kodak found in the laboratory that Tmax was linear out about 20 stops. Well beyond what you could print in the darkroom. Density well beyond what any commercial scanner could read through. So esentially, it's infinite. Well beyond the SBR you'd need in your worse case real life scenario.
  3. What do you mean by 'detailed'? I think the easily usable range is somewhere around 8-10 stops (when you develop it), but as Bruce has mentioned, the film can capture more than that.
  4. Thanks Bruce, i have read that too, but it is unlikely to be 20 stops in camera..... maybe it is with some tricky processing and paper combinations. I'm looking for a realistic in camera exposure latitude range. And in particular what it is for detailed highlights V's detailed dark areas.
  5. Neal by "detailed" i mean still able to capture detail in the darkest shadow area on the neg before it goes to pure black. And by "in camera" i mean with standard processing with out me needing to do any adjustment in development.
  6. The film speed is what it is, so there's no latitude at the bottom. You have to expose enough to record the shadow detail you want, and it won't be much different from any other film. See the usual Zone System references if you want to pin this down further. On the top end, the film can go way further than you'll ever be able to print on paper, but that doesn't mean it's usable density. As you over expose, the image quality in terms of sharpness, grain and other things, will decrease markedly. The camera will also have a flare contribution that limits dynamic range. Now, the final kicker. Getting that long linear curve may require more development than gives optimal image quality. IOW, the diluted and/or low contrast development that many people like will result in an early shoulder and lower Dmax that actually reduces the dynamic range, contrary to what some people think it does. The bottom line is still the old adage of expose for the shadows and develop for the highlights. In fact, though TMax can be processed for a long linear curve suitable for copy work, it's not a film I associate with the word "latitude". It is, in fact, very fussy about accurate exposure and processing.
  7. Hi Steve,
    I hope you'll excuse me for suggesting your question is difficult to answer as framed. Film has no intrinsic "dynamic range" "in-camera", because there is no way to measure the effect of exposure before the film is developed. There is a range of illuminances in a scene to be photographed, and from that information exposure and development can be planned to interpret the scene in any number of ways. The only event to take place in-camera, is exposure, and exposure is not expressed as a range, but as a discrete value based on the quantity of light that reaches the film. I can speculate about your intended meaning and answer that a "normal" range of illuminances is on the order of seven stops, and film exposed under those conditions and developed to "normal" contrast (about CI .56 for diffusion enlargers) will retain detail throughout that seven stop range. There is an enormous amount of information about Kodak products available at their website. Good luck!
  8. Neal by "detailed" i mean still able to capture detail in the darkest shadow area on the neg before it goes to pure black.
    That's up to you. You have to define what part of the scene is "shadow area" and make the proper exposure so that the shadow area you picked has detail.
    And by "in camera" i mean with standard processing with out me needing to do any adjustment in development.
    That is a non sequitur. There's no such thing as "standard processing" for B&W materials. You have to decide what developer to use, what temperature to use, what type of agitation, how long in the developer, all that. All of these are adjustments to development. Determining these variables and executing your resulting workflow is your responsibility. And the workflow that you choose and implement is what determines how much negative density you develop and thus how much highlight detail you get.
    Said a different way, depending on how you choose to process a piece of film, you can make a full range print from a scene that has a subject brightness range (SBR) of 1 stop, 15 stops, or anything in between. For the most part it's under your control.
    It all comes down to that old saw: Expose for the shadows and develop for the highlights.
    The point I'm trying to make, as inarticulate as I may be in trying to make it, is that there's no fixed relationship between the SBR of the scene, and the density range on the film. That relationship is fluid, and is under the control of the photographer.
    Why it works this way is covered in most of the Zone System books. Adams' The Negative is very through and covers it all if you can make it through his prose. Picker's Zone VI Workshop is a simpler and more susinct explanation. There are of course many others.
  9. I have placed a 15 stop brightness range on 8x10 format TMax 100 and kept detail at both ends of the scale. In zone system speak it is merely a N-5 contraction. The secret is to give sufficient exposure, I rated TMX at EI=3, and to develop in a low energy developer. I used Xtol 1+10.
    The result is the flattest most miserable looking negative. Detail is everywhere but the internal contrast is so gutless that it is just plain not worth looking at. By the time the 200 or 300 odd density steps in the negative are translated into the 25:1 reflection density of a gelatin-silver photograph the tonal steps get even closer and more disappointing.
    Sensitive materials can handle enormous photometric challenges but squeezing a 15 stop scene onto 5 stop photographic paper is no way to entertain the eye.
  10. Maris, indeed. Just because we can, doesn't mean we should! ;-)
  11. DR is defined as Density Range. White to black in shadowless light is 1.80, 6 full f stops. In a normal daylight condition of 8:1, this adds 3 stops or a DR of 2.70 or 9 full f stops (scientifically, you can add white or lighter tones but not black which is defined as 0 reflection).
    Proper exposure and development should yield a negative with a GBar of .50, a net density of .70 in middle grey and should print full scale on a world standard #2 paper with a DS (Density Scale) of 1.00. Some non-world standard #2 papers are listed as DS 1.20 which is in reality is, #1 contrast and frequently this litle tid bit is added "some careful workers will prefer #3 paper". ANSI did this some years ago, but fortunately, most manufacturers ignored that little bit of stupidity.
    All of this assumes an enlarger that is either condenser or condenser emulating (variable contrast enlargers), if printing with a diffusion or cold light enlarger, the whole world changes and much additional testing must be used, also cold light enlarges don't change contrast very well.

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