Condenser enlargers: Kodak

Discussion in 'Kodak' started by Michael Scarpitti, Jul 28, 2003.

  1. I never use it, Forte is better suited to my printing.
    I also like Azo.
    Yes, judging from your responses, you like the "edge" definition of grade 3.

    Yes, my pont is it can be measured with sensitometry.
    More accurately stated , it may be more pronounced as a a result
    of condensor enlarger use.
    I'm glad you know this too.

    Few photographers have spent as much time testing BW paper emulsions
    as I have, when I worked for Omega/ Satter on average I might test 30 to
    sixty a month. I like this newsgroup becuase their are a lot of knowledgable
    people here, and in general helpful also alot less bickering here than some of the
    others.
     
    Gregory W. Blank, Jul 31, 2003
    #21
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  2. This is not an inquiry. It's posted to explain why you should follow
    Kodak's advice. I'm telling, not asking.
     
    Michael Scarpitti, Jul 31, 2003
    #22
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  3.  
    Paul Repacholi, Jul 31, 2003
    #23
  4. message
    I thought there was a previous message in the thread.
    The above Kodak data sheet is the one for T-Max and T-Max
    RS developers. The section you refer to states:
    PROCESSING
    The development times in the following tables are starting
    point recommendations. They are intended to produce a
    contrast index of 0.60 for KODAK PROFESSIONAL T-MAX 400 Film
    and 0.56 for the other films. These development times should
    produce negatives with a contrast suitable for printing with
    a diffusion enlarger. To adjust contrast for printing with a
    condenser enlarger, reduce the development time by 20 to 30
    percent.

    This is simply to compensate for the Callier effect.
    Exactly identical results will be gotten with a condenser
    enlarger by printing on Grade 1 paper. However, it is
    sometimes convenient not have to use a less contrasty paper.
    The instructions should also point out that if you reduce
    development as directed you should increase exposure by
    about 3/4 stop. This _is_ pointed out in other Kodak data
    sheets.

    Also, the material from Fine Arts Photo Supply re: cold
    light heads is wrong. First, the Callier effect is not the
    result of dispersion of light but rather scattering. It
    states that diffusion sources are linear while condenser
    sources are not:

    "Prints made from cold light heads reproduce tone in a, more
    or less, linear manner. All tones reproduce in their correct
    proportion. Condenser enlarger prints show a
    disproportionate increase in density in the higher values:
    Zones VI and up print about 2 zones higher in tone."

    Further it suggests as a test not a comparison of two
    enlargers but of a contact print vs: an enlargment. Contact
    prints will have lower contrast in general than condenser
    enlarged prints again due to scattering of light by the
    silver particals. All this scattered light reaches the paper
    in contact printing where it does not in a condenser
    enlarger. Whoever wrote this has no understanding of either
    optics or the printing process. In fact, you can make prints
    with identical tonal rendition in this test by adjusting the
    paper contrast. The idea that condenser enlargers can
    produce nothing by "soot and whitewash" prints is plain
    bull.

    This is just plain wrong. It is a misunderstanding of the
    optical principles involved, of the Callier effect and has
    been proven wrong a great many times. Dr. Richard Henry, in
    his well known book _Controls in Black-and-White
    Photography_ describes a well controlled experiment showing
    that EXACTLY the same density curve results from either type
    of illumination provided that _either_ the negative or print
    contrast is adjusted. If you think the two types of prints
    look different I guarantee you that neither you or anyone
    else will be able to tell in a double blind test.

    The idea that there is a difference is often attributed to
    Fred Picker but I think long predates him.

    I should point out that photographic sensitometry, which
    includes densitometry, is extremely well understood. Also,
    photographic tone rendition or reproduction is a very well
    studied field with much literature in easy to find form.
    There really is no excuse for the continued promulgation of
    this sort of nonsence.

    Enough already...
     
    Richard Knoppow, Aug 1, 2003
    #24
  5. Michael Scarpitti

    muchan Guest

    I also read Ctein's Post Exposure about density curve being the same.

    What I'm not sure is, when the negative or paper contrast is
    adjusted, they are getting the same density curve, are these print
    shows the grains the same way, or not. And if paper contrast is
    changed, then the silver halide compositions on the paper are
    probably not exactly the same, so they would react differently
    with toner, etc., right?

    So, saying that condenser and difuser head may produce the same
    density curve, it may not mean that the result is exactly the same,
    isn't it so? (when they are different, I don't say which is better...)


    muchan (planning to build a DIY head with LED...)
     
    muchan, Aug 1, 2003
    #25
  6. One really has to isolate each variable, before one can make any
    kind of judgement. That means many tests and much attention
    to the detail of assuring that the tests are controlled in each step.
    One mis step and the results are less than accurate.

    I have seen differences in paper prints using various light sources
    but "similar" filteration which indicates incompatiabilty with the
    specific light source, i.e cold light flattening of mid range tones, where
    no matter how much filteration was "pumped" into the projected image
    those mid tones remained flat and unseperated.
     
    Gregory W. Blank, Aug 1, 2003
    #26
  7. I really don't have any use for it.
     
    Michael Scarpitti, Aug 2, 2003
    #27
  8. You obviously missed my point: how would you know?


    --
    We are receiving alerts about a worm that is spreading around the Internet
    contained in a .zip archive file. What is surprising to security analysts
    is that this worm is spreading at all since it cannot execute without user
    intervention. Security analysts believe the rapid spread indicates that
    recipients are still opening email attachments even after they have been
    warned many times that it is unsafe to do so.

    - Description of the "Sobig.E" worm, ca. June 2003
     
    David Nebenzahl, Aug 2, 2003
    #28
  9. For lots and lots and lots of reasons that have to do with with what
    technique is best for getting the best quality out of 35mm.
     
    Michael Scarpitti, Aug 2, 2003
    #29
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