condenser/difusion enlarger question

Discussion in 'Darkroom Developing and Printing' started by 10x, Nov 3, 2003.

  1. So they could get reasonable exposure times on less than speedy papers
    and with non QI bulbs.

    --
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    +61 (08) 9257-1001 Kalamunda.
    West Australia 6076
    comp.os.vms,- The Older, Grumpier Slashdot
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    Paul Repacholi, Nov 4, 2003
    #41
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  2. 10x

    Bob Salomon Guest

    Then let's throw in another wrinkle.

    The Kaiser 6x9 enlargers, as well as some other enlargers, are
    condensor/diffusion systems.

    The Kaiser enlarger uses both multiple element condensors as well as a
    diffusion chamber. First the light from the halogen bulb passes through
    a diffusion chamber and then goes through the condensor system. This is
    true regardless of the head used: black and white with tungsten lamp,
    black and white with halogen lamp, Multigrade with halogen lamp or color
    head with halogen lamp.

    Again both condensors and diffusion chamber are used at the same time.
    This is not the same as an enlarger that can switch from condensor to
    diffusion with a lever.
     
    Bob Salomon, Nov 4, 2003
    #42
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  3. 10x

    John Guest

    It's usually there. It's just that diffusion lights the area surround the
    dust so effectively that its visibility is diminished. That's in contrast to
    the semi-collimated light produced in a condensor enlarger which will
    cause a slight shadow around any obstacle between the condenser
    and the emulsion plane.

    As to why an image made by a diffusion enlarger is just as sharp, it's
    actually quite simple. The lens is the sole determining factor as to whether the
    image is sharp or not. Think of it like this. Would something you see at a
    distance be any less sharp if there were 100 suns in the sky ? No. Your eye
    is the sole determinig focusing agent of the image.

    --

    Regards,

    John S. Douglas, Photographer - http://www.darkroompro.com
    Please remove the "_" when replying via email
     
    John, Nov 4, 2003
    #43
  4. Pat, what do you do about aligning the C760? I have just assembled a
    Chromega XL from a brand new chassis, and chromega head, and used parts from
    ebay... Unlike the junk I have used for five decades I don't see anything
    that looks easily adjusted other than by shimming or bending... Especially
    the spring loaded stage under the negative carrier which leaves me puzzled
    as to how it could possible be even close to aligned...

    Denny
     
    Dennis O'Connor, Nov 4, 2003
    #44

  5. Believe it or not, this is not exactly true. See Thornton's 'Edge of
    Darkness' for the explanation and examples.
     
    Michael Scarpitti, Nov 4, 2003
    #45
  6. 10x

    jjs Guest

    Bob, it has that design in order to minimize a hot spot from the Halogen
    bulb, correct? And where can I find the official info about the Kaiser? Is
    it one of your products? Thanks in advance.
     
    jjs, Nov 5, 2003
    #46
  7. 10x

    Alexis Neel Guest


    nope.

    Alexis

    www.alexisneel.com
     
    Alexis Neel, Nov 5, 2003
    #47
  8. 10x

    jjs Guest

    That's for damned sure. Michael might not notice it because it is far,
    far easier to clean/dust a 35mm negative than a larger format, especially
    MF between glass. I find the Leitz Focomat 35mm to be just fine, and the
    IIa a downright horror story for dust.
     
    jjs, Nov 5, 2003
    #48
  9. 10x

    Bob Salomon Guest

    No it has condensors and the diffusion box for all heads - including the
    one for the 75W tungston lamp.

    Yes we are the importer and you can link to Kaiser from our web page.
    www.hpmarketingcorp.com
     
    Bob Salomon, Nov 5, 2003
    #49
  10. 10x

    Dan Quinn Guest

    I think you must have a very fine focus adjust: dust on the bottom,
    dust on the top, of the film surface.
    With the lens focused on the lower surface of the film, dust on that
    surface shows equally sharp, condenser or diffusion. Dust on the upper
    surface less sharp, and dust upon the upper glass surface prints
    the least sharp.
    The less sharp and least sharp are equall for both condenser and
    diffusion. The apperance of more dust with the condenser is due to
    the directional character of the light and the dust's distance
    from the plane of focus.
    Am I correct in all of the above? Dan
     
    Dan Quinn, Nov 5, 2003
    #50
  11. A few weeks ago, I made a enlargment of a Noblex panorama negative (120x50mm)
    on paper cut from a roll, size about 140cm x 60cm. I noticed a few
    prominent dust particles on the enlargment, tried to find them to remove them
    and found that I had particles between the film and the lower glass, between
    the film and the upper glass and on top of the upper glas. The pictures of these
    particles were definitely different, from sharp-white to fuzzy-grey. I found
    a small piece of hair on top of the upper glass, it was nearly invisible
    in the positive. Another one was sharp and very bright, it was between the film
    and the lower glass. I have an older enlargement of the same negative, it
    shows some of the same dust specks (unfortunately embedded in the emulsion and
    not easily removed) with much more sharpness and clarity. This enlargement
    was made with my older condensor head and a Ilford 500 VC-head on top of
    the condensors. There is no difference in sharpness between both enlargements,
    but I used one gradation harder paper for the second.
    No. With a diffusion enlarger (like my current CLS1000) the dust on top of
    the upper glass (with some 4mm distance to the film and enlarger lens focus)
    appears really fuzzy and only medium grey. With condensor light, a dust particle
    at the same place looks much sharper and darker. Obviously, the collimated
    light makes a strong shadow in the light path, while diffuse light is
    reaching the negative directly under the particle from several paths, so the
    shadow is much more weak and fuzzier. This effect is less pronounced with
    dust nearer to the focus plane, like between film and upper glass. A dust
    particle directly between film and lower glass makes no difference.

    You can easily see the effects of dust in collimated light when looking
    into a microscope ocular. The exit of light here is usually small and
    the light coming from it is strongly collimated, so you see ever speck
    in your eyes (like the conglomerates of blood- and other cells that drift
    on your retina) very sharp and irritating.

    Martin
     
    Martin Jangowski, Nov 5, 2003
    #51
  12. I guess it depends on where the dust is. For dust in intimate contact
    with the negative, it makes little, if any, difference. Scratches are
    a different story, because of the way the negative film base refracts
    light.
     
    Michael Scarpitti, Nov 5, 2003
    #52
  13. 10x

    Dan Quinn Guest

    RE: Martin Jangowski <>

    Unless your enlarger's condenser assembly is an exception to
    the rule, it projects a focused beem of light. My enlarger's condenser
    system has a focal length only a inch or two greater than
    it's diameter.
    That beem of light is a FOCUSED beem. It is not collimated. I know
    what a collimated beem is. I've heard the term so often on this NG
    that when Mr. Knoppow mentioned in one post that the condensors
    actually produce a focused beem, I thought he was likely full
    of Bull.
    I tested my B8 condensor assembly and low and behold, the light bulb
    did come to a focus, and at a short one at that.
    Maintaining a misconception may be fun and games with some but
    for others it might lead to difficulties. Dan
     
    Dan Quinn, Nov 7, 2003
    #53
  14. 10x

    Dan Quinn Guest

    Five corrections need to be made: replace 5 beEm with 5 beAm. When
    in the second grade, poor spelling held up a family vacation while I
    was held after school to write ... and ..., I forget how many times.
    Still spending some after school time. Dan
     
    Dan Quinn, Nov 7, 2003
    #54
  15. 10x

    Alexis Neel Guest

    nope again.

    Alexis

    www.alexisneel.com
     
    Alexis Neel, Nov 7, 2003
    #55
  16. While focused and collimated are not synonymous, a focused beam is *more*
    collimated than a diffusion head... Other than if you have access to a
    laser head, we are working with degrees of more or less diffusion, not
    absolutes...

    Denny
     
    Dennis O'Connor, Nov 7, 2003
    #56
  17. Denny,
    I did something to my enlarger before I had an attack of encephalitis
    that screwed up part of my memory. I remember there was a spring loaded
    stage over as well as under the carrier. Focus was changing with
    temperature even with a glass carrier. I took a piece of 1/16
    duraluminum that you can get from hobby stores where they sell model
    airplane stuff and cut a hole in it slightly larger than the stage
    opening. I bent it so I could mount it above the lower spring loaded
    stage. Now the negative carrier is pressed against the rigid aluminum
    plate by the lower spring stage and always comes back to the same focus
    when I remove it and replace it. Other than that, I have not messed with
    alignment.

    If I can photograph it without disassembling, I will send a picture.
     
    Patrick Gainer, Nov 7, 2003
    #57
  18. 10x

    Dan Quinn Guest

    RE: (Michael Scarpitti) wrote
    That is in accord with Mr. Martin J's posts this thread. Mr. J. has
    closely observed both focus and light source effects where dust is
    concerned. Should read! Dan
     
    Dan Quinn, Nov 7, 2003
    #58

  19. I looked at it again and saw that I didn't have to bend it. It just goes
    between the lamp house and the negative stage. You have to drill some
    bolt holes. It will take less than 6 X 8 inches.
     
    Patrick Gainer, Nov 8, 2003
    #59
  20. Collimation is the act of rendering the light parallel. In other words,
    the light source is imaged at infinity. The first of two condensers does
    this. The second focuses the parallel rays on the iris of the enlarging
    lens in the ideal system. That is why some enlargers, like the 23C, have
    adjustable focus of the lamp.
     
    Patrick Gainer, Nov 8, 2003
    #60
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