Kodak Tmax 3200, Delta 3200 how do they achieve their pushability?

Discussion in 'B&W: Film, Paper, Chemistry' started by Ted Baker, Feb 27, 2018.

  1. Ted Baker

    Ted Baker Member

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    With the re-release of Tmax 3200 and several thread already started...

    I am interested to understand how these films are different, any Ilford or Kodak reps comments most welcome!

    Both these films have an ISO of 1000 or 1200, depending on the developer, so they are obviously more sensitive, a common comment is they have lower contrast at these ISO speeds than what they might otherwise have, but how?

    A film exposed and developed to the ISO standard will have identical density at an exposure Log(1.3) (about 4 and bit stops) greater than the exposure that results in a density of Log(0.1). The two points while arbitrarily chosen are close to a middle tone and deep shadows respectively. So the contrast ratio between these two points should be same for any film exposed and developed to the ISO standard, indeed I believe the correct value is 0.62.

    [​IMG]

    So how are the films different? The ISO test only defines two points, one in/close to the toe and one that would be a mid tone that the films contrast must pass through. That leaves the toe, the path between the two points and all of the density from the mid tones and up, that could be varied, but how?

    Answers on a postcard.
     
    Last edited: Feb 27, 2018
  2. trendland

    trendland Member

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    Ted - from my point you can see a simple Ilford Hp5 as "ultraspeed film" sure you will reach highest ISO's :cool:
    But the characteristic isn't "everybodys darling"
    The grain comes "massive" and tonals are very "contrasty" from my point.
    D3200 has from the beginning a lower contrast to avoid HP5's characteristic at higest speed. Some stated D3200 is foggy at lower speed. That's might be a missunderstanding and is highly dependable from developer.
    So Tmaxx3200 has not this low contrast characteristic at "normal" ISO's.
    The most difference is a finer grain characteristic at all speeds! :surprised:....
    Tonals may increase very high at max.
    speed. Kodak recomanded a tested workflow at higher speeds (ISO 12800 - ISO 25000) but such ISO's [box speed] are very extreme.
    I would like to state to manage tonals is your "task" from developing.
    These films give you just a "basis" on higher speeds.
    with regards
     
  3. michael_r

    michael_r Subscriber

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    Ted, you are quite right. Ilford's film is ISO 1000. Kodak's is ISO 800-1000. The ISO criteria include contrast up to a midtone value.

    What these films (in particular Ilford D3200) feature is lower contrast in the highlights (ie further up the curve than the ISO triangle). You can see this in the characteristic curves. Delta 3200:

    https://www.ilfordphoto.com/amfile/file/download/file_id/1872/product_id/682/
     
    Last edited: Feb 27, 2018
  4. trendland

    trendland Member

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    To answer in addition : Yes they (both) have a much more "sensitive" characteristics. Tmax 3200 has~ 8times more in comparison to Tmax100 for example. The design is made to optimize some different parameter you have to optain within push workflow.
    So (just if I understand your question correct) there is no way from "low contrast films" to use as extreme high speed. [The lower the contrast - the higher the possible reachable ISO].
    THAT IS NO WAY.
    You need the more sensibilisation of the emulsion.
    with regards
     
  5. Gerald C Koch

    Gerald C Koch Member

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    A film's speed is determined by its composition. Factors such as halides present (chloride, bromide, iodide), crystal size, sensitization dyes, etc. For example silver bromide emulsion is faster than silver chloride. Small crystal size produces lower speed. The underlying principle here is the crystal's cross sectional area that is exposed to light. The larger this size the faster the film. With dyes what potion and how much of the spectrum is covered.
     
    Last edited: Feb 28, 2018
  6. pentaxuser

    pentaxuser Subscriber

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    michael_r has kindly given us the Ilford D3200 curve but is there a similar curve available still for the old version of P3200 if we can assume that what Kodak has done is simply to start up the former P3200?

    Thanks

    pentaxuser
     
  7. michael_r

    michael_r Subscriber

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    Here is the tech pub for Kodak TMZ P3200. Curves are toward the end. Looking at the P3200 curves, they don't appear to have the low highlight contrast characteristic of D3200, which means all things being equal, negatives from pushed D3200 should be easier to manage than pushed P3200 negatives.

    http://imaging.kodakalaris.com/sites/prod/files/files/products/F4001.pdf
     
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    Ted Baker

    Ted Baker Member

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    I agree with michael's summary regarding the contrast from mid tones to highlights.

    I think michael, get's what my question is about. In summary a film exposed and developed to the ISO standard will have an identical contrast ratio at exactly the same two points on the exposure scale. Those two points being, one close to the shadows, a density of log(0.1) and on the other point is roughly a mid tone at an exposure log(1.3) greater than the first point, and has a density of log(0.9). If you don't get these values then you did not test the film correctly... :wink:

    So all films exposed and developed to the ISO standard, are identical at those two points, my question then relates to the how are these films more pushable? How do they manage contrast, with extended development but still have the same ISO contrast.
     
    Last edited: Feb 28, 2018
  9. michael_r

    michael_r Subscriber

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    They are more pushable because they are designed (at least in the case of D3200) to have lower highlight contrast, which prevents excessive highlight density from building up when development is extended. Once you push (ie extend development), contrast does increase (ISO criteria no longer satisfied) but it does not increase as much as it would with another film.

    Now, if you're asking about how the emulsion is made to have lower highlight contrast, that's more of an emulsion engineering question than a sensitometry question. I can't answer the emulsion engineering part. That would be a question for Photo Engineer :smile:.
     
  10. ic-racer

    ic-racer Member

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    You graph does not show how D3200 responds differently to under-exposure and over-develompent compared to any other film. Can we see the graph from the other film or what is being compared?
     
  11. pentaxuser

    pentaxuser Subscriber

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    I am not sure if I am reading the graphs correctly but it looks as if the gradient of P3200 in all the Kodak developers continues to rise steeply whereas D3200 in both its Ilford developers levels off markedly by comparison. The curves are not what you might term slightly different but markedly so. The P3200 curves do not seem to level off at all by comparison.

    It may be/may be not that in either of the two Ilford developers P3200 would behave more like D3200 but there is no source to which we can refer.I am unsure how to translate this into practicalities / ease of use when using both films but just basing it on the curves it looks as if P3200 is markedly less amenable to pushing beyond, say, its ISO speed which is why one buys this kind of film in the first place.

    In situations where EI 3200 is required, D3200 is likely to produce negatives more amenable to capturing a range of zones that may require a lot more darkroom printing manipulation if P3200 is used. If the above conclusions hold water then it would seem that where speed is required D3200 is the better( much better?) bet?

    If greater problems arise with P3200 negatives than with D3200, at what speed(1250, 1600 2000, 3200 ) does it become difficult enough to make it the poorer choice compared to D3200?

    I don't suppose that anyone here has done the comparison of shooting both films in similar light conditions at say 1600 then 3200 in the same developer and then tried making prints from the two sets of negs or have they?

    Please bear in mind these are simply questions to extend my knowledge of the two films and how they behave and are not designed to start a fight between Kodak users and Ilford users. I am simply interested in each film's pros and cons.

    pentaxuser
     
  12. Sirius Glass

    Sirius Glass Subscriber

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    I would like to see a shot by shot comparison of the two films.
     
  13. DREW WILEY

    DREW WILEY Member

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    In most cases you're not actually "pushing" anything. You're merely lopping off deep shadow values by underexposure, then raising the density of what's left over through overdevelopment. TMZ would drop you off that cliff into a black hole cleaner, Delta 3200 more on a playground slide.
     
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  15. mdarnton

    mdarnton Member

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    I wonder if the more generic direct answer to the question might be that as a general rule, higher speed emulsions are lower contrast, inherently, than low speed ones, which allows them to be stretched through development. Further, I'm going to guess that the most important limitation for speed is not so much anything else beyond how low will the customers go in quality (grain, sharpness) to gain speed.
     
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    Ted Baker

    Ted Baker Member

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    The problem with the lower contrast explanation at least without some qualification is that it doesn't fit into the ISO definition, a film exposed and developed to the ISO standard has the exact same contrast at the two test points. So a description of contrast needs to have some qualification or explanation, in this context.

    There are obviously many variations that a film can take and still pass through those points, and hence a group of films developed to the ISO standard will all look quite different.
     
    Last edited: Mar 1, 2018
  17. mdarnton

    mdarnton Member

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    But it depends where those measuring points are. What works for their theory may not cover the whole range we use. Do you know?
     
  18. michael_r

    michael_r Subscriber

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    mdarnton: If you're a Zone System user, the ISO measuring points would be Zones I2/3 and VI.
     
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    Ted Baker

    Ted Baker Member

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    The points are precisely defined but they are only two and they do not cover the whole range, just 4 and a bit stops of exposure, I understand the concepts, but I am interested in others expertise, hence the question, answering your question I don't know the answer:smile: ISO is just a system of measurement it is not a theory it is a practical thing, so I am interested in relating a practical measurement to real practical results.
     
  20. Photo Engineer

    Photo Engineer Subscriber

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    Look at the inflection point of the above curve. If you sharpen it, it will then be possible to get the identical upper scale with higher speed and the same contrast. This can be done by development if the emulsions can do this. OTOH, you can put in a lot of silver, and then by proper exposure and development you can get the same general effect.

    This is just a trick that effectively gives higher speed in negative films by taking advantage of pushability by the longer tone scale. It cannot give useful results in a reversal process.

    It is not real speed any way you look at it.

    PE
     
  21. michael_r

    michael_r Subscriber

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    This might help to illustrate. Both film A and Film B have the same ISO speed, but due to the difference in curve shapes, we would tend to say Film B is more "pushable" (ie easier to print when pushed). The Film B curve is similar to that of D3200.

    Pushability.jpg
     
  22. Sirius Glass

    Sirius Glass Subscriber

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    Please help me understand. Are you saying that P3200 is more like film A? Also exactly why is film B easier to print? Is it because film B can fit on the paper while film A has too big a dynamic range?
     
  23. michael_r

    michael_r Subscriber

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    Based on the published curves by Kodak and Ilford, P3200 appears to be more like Film A in my diagram while D3200 appears to be more like Film B.

    Film B has lower highlight contrast. All things being equal, if you were going to push both films, the resultant negatives from Film B might be more manageable because the density range would be smaller. On the other hand if the films were not being pushed, I would tend to prefer Film A because there is less highlight compression when developed normally.
     
  24. jawarden

    jawarden Subscriber

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    That certainly does help, thank you. Always something new to learn.
     
  25. cowanw

    cowanw Member

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    In any case neither Delta 3200 or P3200 have a
    ASA rating; only EI's
     
  26. michael_r

    michael_r Subscriber

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    Actually they do have ISO ratings. D3200 is ISO 1000, P3200 is ISO 800-1000.
     
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