Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,748   Posts: 1,483,772   Online: 781
      
Page 7 of 7 FirstFirst 1234567
Results 61 to 65 of 65
  1. #61

    Join Date
    Aug 2006
    Shooter
    ULarge Format
    Posts
    24
    Hi ic-racer,
    Thanks, an enjoyable thread. Good explanations of those mysterious “ reduce your EI from 100 to 80 and reduce your development by xyz % “ that turn up in various books. Now I know why these work; at least to a degree, a degree of “works” I mean. Not having a working densitometer I live by notes and adjustment, not maybe the best way but I do keep out of mischief and my prints continue to improve.
    Best Regards
    Rob

  2. #62
    David H. Bebbington's Avatar
    Join Date
    Dec 2004
    Location
    East Kent, United Kingdom
    Shooter
    Medium Format
    Posts
    2,364
    Images
    36
    Quote Originally Posted by ic-racer View Post
    Just to restate things a little differently.

    Bill used a method similar to ISO & ANSI & ASA, where the minimum exposure to get a usable negative is determined. This method, by definition leaves no underexposure latitude and all the exposure latitude is for overexposure.

    Sam's technique was that of rating slide film. By definition his method has no overexposure latitude. All his latitude is in underexposure.

    If you 'split the difference' between the two methods you can target you exposure for the middle of the curve, and therefore get 3 stops of latitude for both overexposure and underexposure. Happy Shooting!
    Dear ic-racer, I freely admit that I tried (3 times) and failed to understand your original posting ( I speak as a qualified professional photographer and former technical writer for Ilford Limited). However, I must say that the above statements are total nonsense.

    If you determine exposure on the basis of a shadows reading, then (assuming your reading is accurate) you will obtain correct [minimum] shadow exposure. That is all - there is no direct relation between this exposure and the amount of latitude you can exploit, since this depends on the subject brightness range and the contrast to which you develop the film. If the SBR is "normal" (128:1) and the development is "normal" (G bar 0.55) you will record all tones in a printable form but exposure latitude will strictly speaking be zero (it may be one or two stops, even three, if you are willing to tolerate highlight degradation). If you increase shadow exposure, there will be even less "latitude". The only way to increase exposure latitude is to downrate the film's EI and develop to a lower contrast.

    In the reverse case, basing exposure on a highlight reading will if done correctly ensure correct highlight exposure (maximum possible while retaining detail). Again, with a normal tone scale, there is virtually no latitude except at the expense of shadow degradation. In the case of a transparency shot for projection, latitude is virtually non-existent, there is essentially only one optimum exposure plus a short range of sub-optimum degraded but perhaps acceptable (under-)exposures. Decreasing the exposure can hardly be considered to be exploiting latitude - there are numerous exposures which will record highlight detail, but shadow detail will be hopelessly dark. There is no meaningful sense in which you can draw on 3 stops exposure latitude in both the under- and overexposure directions!

  3. #63
    CPorter's Avatar
    Join Date
    Feb 2004
    Location
    West KY
    Shooter
    4x5 Format
    Posts
    1,662
    Images
    24
    Quote Originally Posted by ic-racer View Post
    Just to restate things a little differently.

    Bill used a method similar to ISO & ANSI & ASA, where the minimum exposure to get a usable negative is determined. This method, by definition leaves no underexposure latitude and all the exposure latitude is for overexposure.

    Sam's technique was that of rating slide film. By definition his method has no overexposure latitude. All his latitude is in underexposure.

    If you 'split the difference' between the two methods you can target you exposure for the middle of the curve, and therefore get 3 stops of latitude for both overexposure and underexposure. Happy Shooting!
    What exactly is it you are trying to convey to potentially 25,000 other members?

    I would pass this on to folks who are new to film. I lack the skills to put it any other way but, IGNORE IT!! You will experience no gains in your understanding of exposure and development if you don't----only headaches.

    The phrase "expose for the shadows and develop for the highlights" is an old, but very true, principle in photography. There's different ways to apply that principle i.e., ZS or BTZS, or simply overexpose and underdevelop, with the latter practice being a much less refined application of the principle than ZS or BTZS. So, get the most out of your film of choice and expose for the shadows and develop for the highlights. It works quite well.

  4. #64
    CPorter's Avatar
    Join Date
    Feb 2004
    Location
    West KY
    Shooter
    4x5 Format
    Posts
    1,662
    Images
    24
    Quote Originally Posted by CPorter View Post
    ..... film of choice and expose for the shadows and develop for the highlights. It works quite well.
    referring to "negative" film, of course.

  5. #65
    pellicle's Avatar
    Join Date
    May 2006
    Location
    Finland
    Shooter
    4x5 Format
    Posts
    370
    Images
    16
    Quote Originally Posted by CPorter View Post
    ..... film of choice and expose for the shadows and develop for the highlights. It works quite well.
    Hi

    strangely, when I've tried altering development by extending development for extending the contrast I didn't get much change, getting only minor extension in the dark areas.
    {double time development}
    I've found on my 'densitometery' that I have a useful range of exposure which is limited by the base fog (if that's the right term here) in the shadows {meaning I can no longer tell the difference between image and murk}. I'm limited in the density where I can no longer tell the difference between fully over exposed film and highlight detail. Something like this range.

    (give or take at the boundaries)

    As shown above my density barely shifted with double time N+ development. Perhaps my mistake was to have exposed a scene with too much contrast for this experiment? Perhaps I'll repeat this again if anyone thinks this might be my root cause.
    Theory: you understand why it should work but it doesn't
    Practice: it works but you have no idea how
    Here theory and practice meet, things don't work and I don't know why
    Homepages: here Blog: here

Page 7 of 7 FirstFirst 1234567


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin