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  1. #11

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    davetravis,
    if you like to know the exact magnification ratio of an arbitariy negative clip to an arbitraty print size, simply replace the negative by a transparent ruler and measure the projected scale.

  2. #12

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    This is one thing I have never thought about. I just adjust height for the crop on the print size. Magnification factors have never been a concern to me. Than again I havent done anything under 4x5 for years.

  3. #13
    Dave Miller's Avatar
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    Magnification adjustment factors are only of interest if you wish to change your enlargement size without producing a second test print(s). Negative size is irrelevent.
    Regards Dave.

    An English Eye


  4. #14

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    vet173,
    this could be of interest for several reasons, which do not necessarily have to do with enlarging itself. It could be necessary to know the scale of a reproduction or to produce an exact 1:1 reproduction. Of course, you'll have to know the exposure mag ratio in this case as well.

  5. #15

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    Thanks for the info. I use an ilford exposure meter for exposure determination. It's only an obsession with me not a job, so I don't do any product photography. I can see now where someone might need that kind of information.

  6. #16
    davetravis's Avatar
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    I needed to know the mag factor so I could decide if I wanted to switch to an APO lens. My Rodagon 80mm is best around 6X. My 16x20's come to around that. My 20x24's are around 9X. The APO Rodagon is best around 10X.
    Since the detail and contrast that I'm getting now printing on Ilfochrome is so fantastic, I have decided that the APO would be a waste of money for my current format. Besides, Ciba doesn't need any more contrast!
    Thanks to all for responding.

  7. #17
    jeroldharter's Avatar
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    Split contrast

    Would the same calculations aplly to each exposure of a split contrast black and white print?

    For example if I make an 8x10 print at f11 with 6 seconds Magenta 200 and 4 seconds Yellow 200; and then I want to convert to 16x20 I should do the arithmetic and apply it to each exposure?
    Jerold Harter MD

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