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  1. #21
    mhulsman's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    Unfortunately impossible. The advertising claim is referring to the, so-called, speed point, which is part of the ISO standard but has little in common with actual printing practise. The exposure compensation required for contrast changes differs with paper and target tonality. Of course, the VLS 501 is unaware of both.

    One can read similar claims about contrast filter sets, but those claims are misleading too. It only works if you want to keep the speed-point density consistent, and who wants to do that?
    Ralph,

    I do not go that deep into the technical details as you do.
    I alway's make test strips the way you describe in your book with the test-strip printer and use F-stop timing.
    I dial on the VLS501 a harder or softer grade, and do a test print on 13x18cm paper. (with the head focussed for the large final print)
    If that is fine I make the final print.
    That is working for me right now. Not that technically bit it works for me.
    --Mike

  2. #22
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    Quote Originally Posted by mhulsman View Post
    Ralph,

    I do not go that deep into the technical details as you do.
    I alway's make test strips the way you describe in your book with the test-strip printer and use F-stop timing.
    I dial on the VLS501 a harder or softer grade, and do a test print on 13x18cm paper. (with the head focussed for the large final print)
    If that is fine I make the final print.
    That is working for me right now. Not that technically bit it works for me.
    I'm a big fan of test strips. Actually, I advocate doing different test strips for different areas of the print (sky, shadows, faces etc). That always works well. I just try to avoid doing them all over again when optimizing contrast, hence, the exposure compensation table. In a way, of course, the tabel is a test strip by itself, just one you can use over and over again.

    Yes, you need to do them for all papers (I only use two types of paper). I also made them for Zone VII and Zone VIII, because, keeping highlights and light skin tones consistent requires different tables. But, you can simplify the process by just making one for your 'target' print tone.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  3. #23
    MattKing's Avatar
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    To satisfy my curiosity ...

    Are the "auto" functions in the OP's enlarger likely to make corrections that are seriously misleading, or can they be used to "help"?

    By this, I mean, can the OP create the tables that Ralph talks about, with the auto functions turned on, and end up with tables that require less supplementary correction than using the enlarger manually?
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  4. #24
    RalphLambrecht's Avatar
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    Quote Originally Posted by MattKing View Post
    To satisfy my curiosity ...

    Are the "auto" functions in the OP's enlarger likely to make corrections that are seriously misleading, or can they be used to "help"?

    By this, I mean, can the OP create the tables that Ralph talks about, with the auto functions turned on, and end up with tables that require less supplementary correction than using the enlarger manually?
    Matt

    Take a look at my graph in post #8. My tables adjust for the speed differences at Zone VII or VIII density. The 'auto' function in enlargers and filter sets adjust for the speed differences at the speed point density.

    It's unlikely to help. On the other hand, as Marco says, I might be too picky. After all, I optimize print exposure to 1/12 f/stop and print contrast to 1/4 (sometimes 1/8) grade. To me, any larger of a difference and the print screams for help. Others may be more tolerant.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  5. #25
    ic-racer's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    Matt

    Take a look at my graph in post #8. My tables adjust for the speed differences at Zone VII or VIII density..
    A table or enlarger head that pivots on such a high value would be non-intutitive. As contrast changes are commonly changes that make darks darker and lights lighter without overall impression of the print being darker or lighter. If you are keeping the lighter values constant then the overall print will look darker or lighter as contrast changes. That does not satisfy the common impression of a 'constant exposure' system.

    Not saying its not a good system, just that is not what most would call a 'constant exposure' system.

  6. #26
    Marco B's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    It's unlikely to help. On the other hand, as Marco says, I might be too picky. After all, I optimize print exposure to 1/12 f/stop and print contrast to 1/4 (sometimes 1/8) grade. To me, any larger of a difference and the print screams for help. Others may be more tolerant.
    Ralph, I don't think you are necessarily "to picky", your prints are testimony to the the high quality you achieve through your working methods, however, I do think most people like you say will be more tolerant, and just not experienced enough to get near this level of control.

    Although I consider myself now a quite experienced printer, I certainly don't see myself capable at this moment to achieve similar control (at least not until I bought and read your book from page 0 to 580 ).

    Your remarks about these small tolerances (1/12 F stop, 1/4 grade contrast) do raise another question though: how do you deal with developer exhaustion / use during a printing session?

    From experience, the developer starts working more "soft" when it gets older / is used. Now I assume you start out with fresh developer for each printing section. I can't afford that luxury, and store&re-use whenever possible, especially since most printing sessions are relatively short. I do keep a close watch on activity and total use though and store in full stoppered bottles.

    But even starting with fresh developer each session, you still have a change in contrast with use, that is probably going to exceed your limits.

    Or am I right to assume that this change is actually independent from the exposure changes in your exposure compensation tables? As you probably make a test strip on the chosen contrast, any change necessary to contrast, will be done based on that evaluation, and exposure compensation is applied just as normal... Meaning although with fresh developer you might use grade 2 for the final print, the same print printed at the end of a printing session, might require and get grade 2.5??

    Well, I guess the answer is going to be that you mix up fresh developer from scratch from powdered chemicals just before each session, and refresh so frequently so as to never even get near any sign of developer use or exhaustion...
    Last edited by Marco B; 10-13-2010 at 03:12 AM. Click to view previous post history.
    My website

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  7. #27
    RalphLambrecht's Avatar
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    Quote Originally Posted by ic-racer View Post
    A table or enlarger head that pivots on such a high value would be non-intutitive. As contrast changes are commonly changes that make darks darker and lights lighter without overall impression of the print being darker or lighter. If you are keeping the lighter values constant then the overall print will look darker or lighter as contrast changes. That does not satisfy the common impression of a 'constant exposure' system. ...
    Well, that's exactly the point. I don't want a contrast change that changes tonal values at both ends. I want exposure to only control the highlights and contrast changes to contol the shadows (and only the shadows). That is what this table achieves. That's very intuitive in my mind. Juggling highlight and shadow changes whenever contrast is optimized is too confusing to me.

    By the way, contrast filters do the same thing. Their makers just picked a different common point (0.6>b+f). Whenever you want a 'constant exposure system' you need to pick a constant target density. Selecting a highlight point makes things a lot easier and avoids the need to bounce back and forth between exposure and contrast modifications.

    It's the way I learned printing from Howard Bond and John Sexton. It works well for me. Others may have a different approach.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  8. #28
    RalphLambrecht's Avatar
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    Quote Originally Posted by Marco B View Post
    ... Your remarks about these small tolerances (1/12 F stop, 1/4 grade contrast) do raise another question though: how do you deal with developer exhaustion / use during a printing session? ...
    The answer is called 'factorial development'. It takes care of developer exhaustion and temperature fluctuations.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  9. #29
    ic-racer's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    Selecting a highlight point makes things a lot easier ...It works well for me. Others may have a different approach.

    Yes, and indeed it may be good for novices also. It just seemed a novice reading this thread could be confused. One needs to understand that in that system, the test prints need to be selected that have the correct highlight value when the exposure system pivots on the higher values. And, as pointed out, that exposure system needs to be created from scratch by the user.

    None of the commercially produced constant exposure heads or constant exposure filter systems function that way.

  10. #30
    RalphLambrecht's Avatar
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    Quote Originally Posted by ic-racer View Post
    Yes, and indeed it may be good for novices also. It just seemed a novice reading this thread could be confused. One needs to understand that in that system, the test prints need to be selected that have the correct highlight value when the exposure system pivots on the higher values. And, as pointed out, that exposure system needs to be created from scratch by the user.

    None of the commercially produced constant exposure heads or constant exposure filter systems function that way.
    Correct, except for the products from RHDesigns, such as the Analyzer for example, but you are right, they are the only ones I know of. One possible reason is that the system is easy to execute manually, but much harder to automate due to the non-linear variances in papers. The Analyzer works this way by calibrating each paper once. It's the same thing as making oneself the table for manual exposure compensation.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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