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Thread: PQ Universal for HP5+ and/or Pan F+

  1. #11

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    Re: PQ Universal for HP5+ and/or Pan F+

    Quote Originally Posted by Pere Casals View Post
    Jim, yes...

    I guess that the right answer to OP is 1:19 / 4min for Normal contrast, but 1:9 if he wants higher than normal contrast.

    It's nice to see that Vaughn is using PQ to make negatives for carbon printing, it's a process that I want to learn. I want to avoid digital negatives...

    In the early days the term gamma was used to describe curve slope, and for a straight line part of the curve it is an angle found by dividing the density range of the negative by subject brightness (or subject luminance) range. Most modern films have a limited straight line section so film makers today use other terms. G-bar is Ilford's term for Average Gradient, Kodak uses CI, or Contrast Index. G-Bar and CI are determined in slightly different way but produce similar results, depending on curve shape.

    N, or Normal contrast, is a Zone system term that must be associated with the contrast requirements of negatives for a given process. Film makers don't make that determination, but do provide G-Bar and CI charts that can be used to determine how much contrast one will get with a given film, developer dilution and method, and time of development. These charts can be very useful, if you know how much average gradient or contrast index you need for a given process, and type of lighting.

    Sandy
    http://www.sandykingphotography.com/
    For discussion and information about carbon transfer please visit the carbon group at groups.io
    [url]https://groups.io/g/carbon

  2. #12
    LF/ULF Carbon Printer Jim Fitzgerald's Avatar
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    Re: PQ Universal for HP5+ and/or Pan F+

    Quote Originally Posted by Pere Casals View Post
    Jim, yes...

    I guess that the right answer to OP is 1:19 / 4min for Normal contrast, but 1:9 if he wants higher than normal contrast.

    It's nice to see that Vaughn is using PQ to make negatives for carbon printing, it's a process that I want to learn. I want to avoid digital negatives...
    Pere, if you want to learn carbon printing using in camera negatives come to Yosemite October 21-24,2020 when Vaughn and I will be conducting our carbon workshop again. Or you can hit us up for a private workshop as well.

    https://shop.anseladams.com/Carbon_P...p/32201021.htm

  3. #13

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    Re: PQ Universal for HP5+ and/or Pan F+

    I've used it at 1+19 on HP5+ for about 6 mins to boost the contrast of a flat scene for silver printing (and indeed scanning) - no reason why you can't use 1+29 or 1+39 to get the development time extended to a useful time. If you look out Paterson's data sheets for their FX-26 'Universal' developer it might also give some handy pointers - contextually there are good reasons for it to be pretty close to PQ Universal in behaviour etc. PQU is not fine grained, but it is extremely low fog & very, very sharp - albeit with a slight speed loss.

  4. #14

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    Re: PQ Universal for HP5+ and/or Pan F+

    Thanks all for getting back to me. Is there a way to calculate extended time for various dilutions? Im assuming 6 min at 1+29 for normal contrast (based on 4 min at 1+19), or maybe 9 min for higher contrast based on interneg's usage?

  5. #15

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    Re: PQ Universal for HP5+ and/or Pan F+

    Quote Originally Posted by pkr1979 View Post
    Thanks all for getting back to me. Is there a way to calculate extended time for various dilutions?
    You have to check it, equivalent times may not be linear. Ideally you should make a film calibration like it is explained in Beyond The Zone System Book, but there are simple practical procedures.

    Easiest way is to expose a 35mm roll (all (say) 24 exposures) with the same scene, use an scene with ample dynamic range. Remove the beginning of the roll, then cut pieces of about 40mm to make tests, you'll have the all scene in each piece but in "halves". Develop the reference scene with the reference dilution, then vary the development time for the new dillution until you find the a very close match.
    Last edited by Pere Casals; 6-Nov-2019 at 05:18.

  6. #16

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    Re: PQ Universal for HP5+ and/or Pan F+

    Quote Originally Posted by sanking View Post
    N, or Normal contrast, is a Zone system term that must be associated with the contrast requirements of negatives for a given process. Film makers don't make that determination, but do provide G-Bar and CI charts
    Sandy, you are right, N is an ample concept, I guess that with silver gelatin paper it is the development that produces an easy to print negative for grade 2 Paper, for Normal SBR scenes, ...but each process should have a different "Normality".

    Perhaps the right wording would had been Standard ISO contrast, 0.62, that is used to calculate ISO box speed.


    Quote Originally Posted by Jim Fitzgerald View Post
    Pere, if you want to learn carbon printing using in camera negatives come to Yosemite October 21-24,2020 when Vaughn and I will be conducting our carbon workshop again. Or you can hit us up for a private workshop as well.

    https://shop.anseladams.com/Carbon_P...p/32201021.htm
    This... would be... fantastic!!! I cannot think a better way (first) to learn and (second) to get extraordiary fun !

    I'm 9,468.28 km far... but perhaps it may be possible, I'm going to think about it.

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