Same negative, different contrast between contact print and enlarged print?

Discussion in 'Enlarging' started by Juan Valdenebro, Feb 13, 2018.

  1. Juan Valdenebro

    Juan Valdenebro Member

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    Hello,
    Is it a common belief?
    Are contact prints in general softer than enlargments if we talk about same negative and same contrast filter for multigrade printing?
    That kind of matches my memories: often my first prints from a negative I checked on a contact sheet, looked harder than I expected: harder than what I saw on the contact print...
     
  2. ic-racer

    ic-racer Member

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    Small format rollfilm negatives are somewhat challenging to print 1:1 to do the comparison. However, 8x10 is easy to print 1:1 with a 300mm Rodenstock Rodagon and a diffusion head, the contrast is essentially the same as the contact print.

    Your results may differ depending on your enlarger and enlarging lens. Let us know what you find.
     
  3. MattKing

    MattKing Subscriber

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    There are more sources of contrast reducing flare in an enlargement than in a contact print.
    However, there are a lot of subjective differences arising from viewing a relatively tiny contact print (from a relatively tiny negative) as compared to viewing a relatively large enlargement.
    From a moderate distance, contact prints lend to look as if they have more "punch" - something that may give the impression of contrast, but like as not may be more related to the contribution that the surrounding black gives to the sense of dynamic range.
     
  4. After modifying my 5x7 Omega diffusion enlarger's light source to LEDs, I made a number of tests with 4x5 Stouffer step wedge to check how it performed with Ilford under-lens filters (which proved to be just right). But I was always wondering about a difference in contrast between a contact and an enlargement, that I'd read about; so while doing these tests I first projected the step wedge for a Gr2 print (masking the wedge as much as possible in the carrier to minimize flare), then made a contact print of the wedge with same Gr2 filter and unchanged enlarger height. Checking the two results with a reflection densitometer showed a definite contrast difference - results of the two prints are shown in the attachment. But I suppose the inherent flare from the enlarger lens/bellows in the projection print could explain the difference - I may never know for sure. BTW, the two curves have been adjusted to intersect at a .09 density in order to show the difference in slopes more easily. Notice that it shows at RLE 1.7, for example, the difference in the blacks is substantial (density of 1.45 represents Zone III + 1/3) - even though the highlights are unchanged. A density difference of 0.3 is one zone. Also, these measurements were done on DRY prints, so the effects of dry down are included.

    Projected vs. Contact - Grade 2 (2016_10_09 18_43_47 UTC).jpg
     
    Last edited: Feb 14, 2018
  5. bernard_L

    bernard_L Member

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    OP states that enlarged version looks harder than contact print; Enlarger flare goes to explain the opposite.

    The explanation is what is called the Callier effect. Two things happen when light interacts with the negative.
    (a) some photons are just absorbed
    (b) some are just thrown off course, diffusing off the silver grains; more or less proportional to true absorption, but different.
    Now focus (!!) on (b). When doing a contact print; the (b) photons will reach the paper underneath anyway. So only absorption (a) contributes to contrast. When doing an enlarger enlargement, some of the (b) photons will miss the diaphragm aperture, so ultimately, they are effectively absorbed.

    Ha! and what about enlargers with a diffuse source? Well, some photons initially aimed at the diaphragm aperture will be sent off course, but the reverse also happens: some photons initially doomed to be "wasted" will be sent by diffusion on the silver grains into the diaphragm aperture. More technically, the two will cancel as long as the angular extent of the light source is at least as large as the angular spread of diffusion.
     
  6. RalphLambrecht

    RalphLambrecht Member

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    thought it was the other way around; the contact print having the highest contrast?
     
  7. MattKing

    MattKing Subscriber

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    All of these factors do enter into the equation, but I would suggest that while they may lead to an objective, reflection densitometer based reading result that is in accord with what you say, the subjective differences between viewing several small images with small details surrounded by black on the typical contact proof sheet and viewing a single enlargement with large details including large areas of shadow probably have a greater effect on the perception of contrast.
     
  8. DREW WILEY

    DREW WILEY Member

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    Yes, contacts would inherently have higher contrast. But with VC papers it's easy to tweak either.
     
  9. Theo Sulphate

    Theo Sulphate Subscriber

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    Maybe experiment. Make 8x10 photo, put on 16x20 matte black background, place on wall in darkened room, put light on photo, step back so that image size matches that of viewing contact printed frame, then see if contrast is the same.

    If so, then effect is visual, not physical.
     
  10. mdarnton

    mdarnton Member

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    No matter how flare-free your enlargingsetup is, with an enlarger the image still has to go through air, a lens, and air again before it gets to the paper. Each one of those adds it's own problem to the drive train, and it is not possible to fully eliminate their diffusing, contrast-lowering effects.
     
  11. DREW WILEY

    DREW WILEY Member

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    ...maybe if moss is growing atop the contact frame glass
     
  12. ic-racer

    ic-racer Member

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    The effects of the lens and projection system can be reduced to they are not noticed in the print. If your 1:1 projections don't achieve the same results as a contact print, consider that you have overlooked a source of flare or fog somewhere in the darkroom or projection system.
     
  13. DREW WILEY

    DREW WILEY Member

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    It takes a darn serious enlarger lens to do that. I even keep on hand a variety of lenses to finely tweak color printing contrast, all of them excellent, but some of the Apo ones having noticeably higher contrast. It's really a bit more complicated than just A to B contrast, however; the nature of tonality in-between can also differ. Even available papers are an issue, though I tend to use projection papers for occasional contact printing too.
     
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