Tmax Latitude

Discussion in 'Film and Processing' started by mauro_franic, Nov 6, 2011.

  1. Many people have asked me follow up questions to better understand film's latitude as well as the effects of pushing combined with PS adjustments.
    It is no secret that B&W film rocks in tonality, dynamic range and thus provide awesome latitude.
    I appreciate all the questions people are sending me; but in the interest of time and clarity I decided to contribute with a practical exercise.
    I shot two rolls of TMAX 100 from EI 6 (overexposed 4 stops) to EI 1600 (underexposed 4 stops) in two stops increments. I then developed one roll for 10 minutes in XtoL 1:1 at 75F (this pushes the highlights 4 stops, the high-midtones 2 stops and the low midtones half a stop) and the second roll normally for 6 1/2 - 7 minutes.
    After that curves compensations were applied individually in Photoshop.
    Link to high resolution images:
  2. Impressive results - but I bet it pays off to use a good scanner to get pretty results out of a really thin oder dense negative.
  3. This test is to explain the relationships amongst exposure, pushing and PS adjustment. This test is not to show the boundaries of film's latitude (they are far broader than this example).
    Since many people use flatbeds though, I may run the film through the Epson V500 to share.
  4. Also note that Xtol pushing is mainly effective on the highlights but causes almost no increase in grain. Hence it is great for contrast management.
    Tmax developer as a pushing agent is more effective on the midtones but brings out grain a bit more noticeably.
  5. Run it through the v500 for fun. I expect that the v500 will not do very well with the denser overexposed negs but will do somewhat OK with the under exposed negs.
  6. Thanks for this, Mauro. From my observations, pushing isn't necessary. Am I right?
  7. Karim you are correct for this particular case because of the way tones are distributed (e.g. since the hair and the face are both light tones the contract increase is not so dramatic).
    In other cases pushing really makes the contrast pop. Also using Xtol 60/40 (instead of 1:1 in this case) makes the exposure gain at development stronger (if that is what you are looking for) as 1:1 is not potent enough on a short tank.
  8. Also Karim, if you compare the unadjusted frames relative to each other you can easily determine how pushing affects the highlights, midtones and shadows.
    For example the hair on the 3rd frame is lighter than on the 2nd frame which was shot 2 stops brighter. Hence you may observe that pushing offer a gain of 3 or 4 stops on the hair.
    The scarf on the 3rd frame falls in-between the 2nd and 4th frame. Hence the scarf gain 1 stop during pushing...
  9. I can see that film development can be 50% alchemy. As if I didn't know that already. :) So I suppose that you may as well push, because, if my observations are accurate, the only disadvantage is the extra time that it takes to do so.
    One day I really will start developing my own b&w film...
  10. It is really very simple, gives you a lot of control and takes little time.
  11. James G. Dainis

    James G. Dainis Moderator

    Routine pushing is not a good 1dea unless one has a reason to do so. If one has the full range of zones 1 - 9 exposed on a film and pushes two stops, one ends up with the zones 1 - 7 (though expanded to 9) and blown highlights for the rest.
  12. Amazing Mauro. Goes to show why instant film cameras with no exposure adjustment at all even work.

    Now imagine if those instant cameras were loaded with slide film, LOL ;)
  13. Latitude is so great that shutter speed was not critical for those cameras.
    This post was meant to respond to people that were asking me about the effects of pushing but I guess latitude still steals the show.
  14. What was the metered EV for the scenario in those illustrations? Was it metered with an incident or reflective meter?
    What do the histograms show after some of the more extreme curve, gamma or other adjustments? Any measurable or visible posterizing?
  15. Routine pushing is not a good 1dea unless one has a reason to do so. If one has the full range of zones 1 - 9 exposed on a film and pushes two stops, one ends up with the zones 1 - 7 (though expanded to 9) and blown highlights for the rest.​
    Okay, but does this hold true even if the film is underexposed? I am guessing not, but I admit to being ignorant in some of the finer matters of film processing.
  16. Lex, the meter with the sphere out pointing at the camera showed f8 1/250. This coincided with the evaluative metering of the Canon 7NE.
    You can measure the curves (after adjustment) from the link by selecting the frame you want to evaluate and add a masked curves layer.
  17. It was about 3pm with clear skies (late October 2011).
  18. Karim, there is no need to push unless you are trying to deliberately increase contrast or density on the negative.
    You can observe that the relationship between the hair and face of the doll are very different on the pushed film. Neither one is better - it depends on your objective / preference.
    The same (reciprocal) goes for pulling.
  19. James G. Dainis

    James G. Dainis Moderator


    Suppose you had a scene that would consist of zones 1 - 9 developed normally. If you were to underexpose two stops, all zones would drop down two values.

    Zones 1, 2 (dark shadow with some detail) would drop to zones -1, 0 (pure black no detail) and zone 9 would drop down to zone 7. N+2 development would bring that zone 7 back up to zone 9 but the lower zones would stay at -1, 0 (pure black). Increased development can only affect the highlights, the upper zones, not the shadows, the lower zones.

    I use those figures as an example. Zone 0 is the lowest that one could go. That would register as clear on the film, no tones what ever except for base color and fog. Since zones -1, -2, etc would simply be zone 0 they are not used. .

    Read the first paragraph here so you can "see" what is going on:
  20. James,
    I agree with the first part of your statement that routine pushing is not good practice (without a purpose) since I generally prefer the contrast of Tmax developed on Xtol 1:1 at 7 minutes.
    In 99% of cases there is no risk of blown highlights due to pushing a few stops though. Tmax on Xtol 1:1 has more than 15 stops of DR capabilities. Pushing a few stops would still leave you with vastly more DR than any digital camera can provide.
  21. Other films/developer combinations may not produce densities to capture such broad DR and pushing may be risky. Not so much Tmax/Xtol - not even grain increases materially from pushing.
  22. Lex, where you able to analyze the histograms?
  23. Thanks Mauro again. Interesting samples. But if you bend the curve that much the image may become too noisy. Is this correct?
  24. You are welcome.
    Possibly but I doubt you would see any noise on a print. The curves I applied were a quick visual adjustment - nothing to use as a final product.

    Even under exposing or over exposing film by 4 stops, you are still left with 4 stops on one side and 12 stops on the other of recorded density.
  25. Personally, I do not like Tmax films I find them too contrasty often the highlights are washed out. I tried them in d-76, and T Max RP developers. I admit I have not tried xtol, as I quit using the film at all. I do not use many kodak products anymore, I first became disappointed when they eliminated Pro-100, (PRN) color negative film I have found no current competition for the high color saturation. AGFA Ultra 50 was excellent also, but alas it was discontinued then out came Ultra 100, and I have not tried it yet. I lost all faith in kodak when they discontinued their Tech Pan film, it was the finest grained film I have found when shot at ISO 12 and developed in Technidol developer...
    For B&W film now I am trying efke 25 & 50 ISO films. (as well as 820 Aura IR film)
  26. James, thanks for the link. I never bothered to find out what the zone system was for - and now in a matter of minutes I understood the basics. :)
    I still come away thinking that pushing does not always blow out the highlights - it just depends how strong they are. I guess it depends on the scene... Does under-development cause more grain in the shadows? This b&w processing stuff is really quite interesting.
    Now I appreciate that exposure and development can complement each other. I guess I've always known that but not in a systematic way.
  27. John, please explain what do you mean by washed out and post an example.
  28. Karim, you should try it. If you follow the publication you will find it is very quick and simple.
  29. Under very low light situations, when using TMax 400, I adjust the shutter speed to two stops slower than I want or will be shooting, i.e. 1/15 for 1/60, 1/8 for 1/30 (with a rangefinder). If I get a positive or "slightly positive" reading I am confident, and have been successful. That is with normal processing at a professional lab.
  30. Steve, I do not understand your comment. Can you please expand?
  31. James G. Dainis

    James G. Dainis Moderator


    I have to apologize to you. This is a valuable thread that you started which took much work on your part. I was a bit slow on the uptake and it took me a while to realize one person was using several names or sock puppets to disrupt the thread. I had upper admin look at it and when another account was opened today by the same person under another different name to add another argumentative and sarcastic post, that was enough. The user accounts have been deleted from the community and this thread has been cleaned up.

    Again, I apologize. I should have caught it a lot sooner.
  32. Thank you.
    Sometimes is hard to distinguish between someone looking for honest understanding and someone just intentionally trying to derail a topic.

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