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  1. #1

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    ISO speed of paper (negatives)

    Hello,

    I would try to use paper as a negative, apparently this can give interesting results. However I seem unable to find the ISO speed for paper. How do you determine the correct exposure (camera exposure, not print exposure) for a paper negative? Is this just a matter of trial and error or are there tables (or guidelines) for this?

    Thanks,

    Jan

  2. #2
    Ian Grant's Avatar
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    Papers vary in speed from around 2-10 EI.

    Ian

  3. #3

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    Thanks, that gives me something to start experimenting.

  4. #4

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    some paper is around asa 25 ... some is really slow ( less than 1 )
    it reads blue light so it can be a bit tricky ...


    http://www.apug.org/forums/forum42/6...-goodness.html
    http://www.apug.org/forums/forum37/6...-negative.html
    http://www.apug.org/forums/forum62/5...so-rating.html
    http://www.apug.org/forums/forum44/5...tives-4x5.html
    http://www.apug.org/forums/forum205/...negatives.html
    http://www.apug.org/forums/forum42/4...negatives.html
    http://www.apug.org/forums/forum42/2...-question.html

    just do a search with "paper negative" in quotes and you will find
    pages and pages of fun stuff about paper negatives ...

    and the paper negative group too

    http://www.apug.org/forums/groups/paper-negative.html

    good luck!
    john
    im empty, good luck

  5. #5
    ic-racer's Avatar
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    Well, since you will be using it as a 'negative' and presumable passing light through it, I'd test it just like a piece of film. Do a series of zone I exposures at various ISO/ASA settings. Then place the processed paper over an exposure meter (or densitometer) and select the zone I exposure that cuts light by one-third of a stop (0.1 log density).

  6. #6
    RalphLambrecht's Avatar
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    Quote Originally Posted by jankeirse View Post
    Hello,

    I would try to use paper as a negative, apparently this can give interesting results. However I seem unable to find the ISO speed for paper. How do you determine the correct exposure (camera exposure, not print exposure) for a paper negative? Is this just a matter of trial and error or are there tables (or guidelines) for this?

    Thanks,

    Jan
    I use Ilford MGIV-RC rated at 3 EI. My lightmeter luckly goes down that far. To cut the contrast, use a yellow filter and drop the speed to 2. Develop with highly diluted paper developer (25-50% of normal concentration) to make the negatives. Contact print with emulsion-side down and develop the print in normal-strength developer.
    Regards

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

  7. #7
    Photo Engineer's Avatar
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    I shoot Ilford MGIV paper at ISO 25. I've used it in my Speed Graphic and also in my RZ.

    PE

  8. #8
    ajmiller's Avatar
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    Mark Tweedie, who I think posts on the forums here, has a great article on paper negatives which I used recently and it seemed to work ok for me.

    Link

    - Tony
    regards,

    Tony

  9. #9
    RalphLambrecht's Avatar
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    Quote Originally Posted by ajmiller View Post
    Mark Tweedie, who I think posts on the forums here, has a great article on paper negatives which I used recently and it seemed to work ok for me.

    Link

    - Tony
    Thanks for the link Tony, good article.

    Mark talks about flashing or fogging the paper prior to exposure in his article. That helps tremendously to control contrast with fixed papers, but I have seen no need to do so with VC papers. A yellow filter takes care of contrast with VC papers in my experience.

    Also, whenever fogging the paper prior to camera exposure is necessary, it is easier to do that right in the camera and not in the darkroom. I built myself a special filter for that, taking an old filter and replacing the glass with a milky plastic reading exactly -2 stops. Make an exposure through the filter first, and without changing the exposure settings at all, take the filter of and follow it up with the image-taking exposure. This, in fact, equals a Zone-III pre-exposure and replaces the proposed pre-exposure in the darkroom. It works great for me.
    Attached Thumbnails Attached Thumbnails FogFiltersDIY.jpg  
    Regards

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

  10. #10

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    ralph ...
    that is a great pre-flash filter you have there!
    i spoke with an old timer years ago who used to pre-flash his
    slide film with a milk glass filter just like that. all the people around him
    were wondering " what the heck is this guy doing ?! " and then when they
    saw his chromes they were in awe of how "full" they were.

    i tend not to pre-flash my paper.
    while i know it is probably helpful, i just shoot my paper negatives in situations
    where i either WANT some elements to be blown out and others ... not
    or in situations where the light is even.

    like mark speaks about, i also use exhausted developer, but i also use a double bath, so
    once the image begins to show itself with the exhausted developer, i water bath it, and then finish
    it off in fresher developer ... it's probably not necessary, but fun just the same ...
    and i find that old paper that might be fogged a bit tends to take a bite out of the contrast

    john
    im empty, good luck

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