ISO speed of paper (negatives)

Discussion in 'Alternative Processes' started by jankeirse, Apr 10, 2010.

  1. jankeirse

    jankeirse Member

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    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. Ian Grant

    Ian Grant Subscriber

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    Papers vary in speed from around 2-10 EI.

    Ian
     
  3. jankeirse

    jankeirse Member

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    Thanks, that gives me something to start experimenting.
     
  4. ic-racer

    ic-racer Member

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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).
     
  5. RalphLambrecht

    RalphLambrecht Subscriber

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    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.
     
  6. Photo Engineer

    Photo Engineer Subscriber

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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
     
  7. ajmiller

    ajmiller Subscriber

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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
     
  8. RalphLambrecht

    RalphLambrecht Subscriber

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    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.
     

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  9. jnanian

    jnanian Advertiser Advertiser

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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 :wink:

    john
     
  10. RalphLambrecht

    RalphLambrecht Subscriber

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    We use the same paper, and I shoot at 3, but you shoot at 25. I wonder where that difference comes from? Different developer? I use Dektol at either 1+4 or 1+7.
     
  11. RalphLambrecht

    RalphLambrecht Subscriber

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    Thanks

    I forgot to mention that the milky plastic (shown in picture) is a box cover from IKEA.
     
  12. Photo Engineer

    Photo Engineer Subscriber

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    Here is the original paper negative from a scan and the reversal image courtesy of photoshop.

    PE
     

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  13. jnanian

    jnanian Advertiser Advertiser

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    hi ron

    what kind of lights do you use to illuminate your chart ?

    i have found certain light conditions my paper is "faster" than others
    (more blue? ) .

    john
     
  14. RalphLambrecht

    RalphLambrecht Subscriber

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    Am I the only one missing how attachements could be viewed in APUG?
     
  15. Photo Engineer

    Photo Engineer Subscriber

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    That was a daylight exposure.

    All you need do is click on these and they appear on-screen in a new window or an overlay depending on your browser.

    PE
     
  16. RalphLambrecht

    RalphLambrecht Subscriber

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    What I meant to say was:

    'Am I the only one missing the old way how attachements could be viewed in APUG?'

    Sean apparently changed it, because it was creating a problem with the classified.
     
  17. Photo Engineer

    Photo Engineer Subscriber

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    I forgot to mention that these were developed in Dektol 1:3 for 1 minute.

    PE
     
  18. goldenimage

    goldenimage Subscriber

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    I usually rate mine at iso 6 (arista edu ultra grade 2) i have for the most part have had great results with it, i just dont include much if any sky in my images due to extremely small latitude.
     
  19. RalphLambrecht

    RalphLambrecht Subscriber

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    Try a yellow filter. It will make all the difference in latitude (but cuts the speed in half).
     
  20. Loris Medici

    Loris Medici Member

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    The rule of thumb was to use a EI value equal to ISO paper speed / 100 IIRC...

    This paper has a relatively higher speed than the others. Unfiltered P640 -> EI 6-7, filtered P250 -> EI 2-3. (w/ filters between 00 and 3.)

     
  21. sanking

    sanking Member

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    Some years ago I found at a surplus store several hundred sheets of single weight 20X24" Kodabromide, single weight, grade 3 and bought it for next to nothing. It seems to work nicely for making paper negatives as it prints nicely with no weave pattern. I rate it at ASA 4 and develop in D72 1:4. The base density of the paper is log 0.60 so shadow density will be a minimum of about log 0.90. This makes exposures about three stops more than film.

    Dmax will get up to about log 2.9 with light objects on a sunny day so yous get a DR of about 1.8 or 1.9, which is nice for printing with a UV process that requires a contrasty negative.

    Sandy King
     
  22. sanking

    sanking Member

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    Some years ago I found at a surplus store several hundred sheets of single weight 20X24" Kodabromide, single weight, grade 3 and bought it for next to nothing. It seems to work nicely for making paper negatives as it prints nicely with no weave pattern. I rate it at ASA 4 and develop in D72 1:4. The base density of the paper is log 0.60 so shadow density will be a minimum of about log 0.90. This makes exposures about three stops more than film.

    Dmax will get up to about log 2.9 with light objects on a sunny day so you get a DR of about 1.8 or 1.9, which is nice for printing with a UV process that requires a contrasty negative.

    Sandy King
     
  23. Joe VanCleave

    Joe VanCleave Member

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    I use Freestyle's Arista brand grade 2 paper, rate it at EI=12, with the caveat that the developer be freshly mixed at 1:15 at 68f, and I also perform a slight preflash.

    For daylight exposures the EI=12 recommendation with this paper works out pretty linearly, from bright sunny exposures to deeply shaded, regardless of whether the camera has a f/300 pinhole or a f/8 glass lens.

    Where the metering gets wonky is indoor, incandescent lit still-lifes, where there's very little blue/UV in the light source, thus the light source's spectrum doesn't match the paper's response curve very well, and my handheld meter is full-spectrum sensitivity. I've thought of placing some sort of blue filter over the meter and doing a set of calibration tests under incandescent lighting.

    ~Joe