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  1. #21

    Join Date
    Sep 2002
    Location
    Willamette Valley, Oregon
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    Medium Format
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    Quote Originally Posted by Ronald Moravec View Post
    Not all enlarging lenses have flat fields.
    Also enlarging lenses have a best enlarging diameter.
    Departure from optimum may exacerbate the problem.
    I note the OP mentioning moving to greater diameter
    enlargements. Dan

  2. #22

    Join Date
    Jan 2005
    Location
    Downers Grove Illinois
    Posts
    1,053
    If there is a hump, the metal is stretched. Beating it down can at best make it pop the other way.

  3. #23
    jeroldharter's Avatar
    Join Date
    Nov 2005
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    Wisconsin
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    Many people have chimed in on this thread. I appreciate all of the input. Some have sent me detailed PM's which are very thoughtful and appreciated. Sorry I have not responded to them individually.

    At this point I am not having any problems. I think I was having a combination of issues. The easels are slightly bowed, but very slightly and not enough to make a difference normally . Also, I think the the 4x5 negative in the carrier was not popped but bowed. I use a Negaflat carrier which is excellent for flatness but I had the negative sitting in the carrier at least overnight without re-setting it so I think it sagged a little. Also, I had aligned my lens with the Beseler tool but then I ponied up and bought the Verslab which is much more precise. I still don't have it perfectly aligned but very close. And I stopped my lens down a little for good measure as well as for base exposure times in the 20-30 second range which I like.

    So the combination of adjusting the negative in the negaflat, aligning the negative and lens with the Versalab, and using f11-16 on the lens has done the trick, at least up to 16x20 prints which is as large as I plan to go (except for the occasional 20x24 of course).

    So thanks again for all of the ideas and thoughtfulness of replies.
    Jerold Harter MD

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