How to read the Durst scale numbers

Discussion in 'Enlarging' started by Helinophoto, Feb 21, 2012.

  1. Helinophoto

    Helinophoto Member

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    Hi

    Tried searching, but I didn't come up with much useful information on the subject.
    I have a Durst m670 BW, which I now (thanks to good helpers on and off APUG :smile: ) have both lens and condensers and negative carriers for, to go from 35mm, to 6*6 to 6*7.

    All is dandy, really, but I have a question about the numbers on the column scale on the enlarger and how to interpret them.

    This is how it looks:
    bilde.jpg

    f50 f105 and f80 are easy, these point to the lens used.

    I assume that the numbers inside the squares are some kind of enlargement factor? (if so, compared to what really, what do they mean in every day printing?)
    There are also numbers to the left and to the right of the squares (inches/cm?), do they just indicate the enlarger head height, or do they give away more information than that?

    If someone knows, please enlighten me, I didn't get the manual with this enlarger :/

    Printing is going very well though, but understanding these numbers may make it even easier to work in the dark ^^
     
  2. ic-racer

    ic-racer Member

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    Those are linear magnification scales.
    For example at 39cm you are at 19x with the 50mm lens.

    Knowing your magnification is important for choosing an enlarging lens. When you are outside the manufacturer's magnification specs for a lens, you are likely to have difficulty with blurry corners.

    For example if you have the popular Rodenstock Rodagon 50mm f2.8 lens, you will be exceeding the manufacturer's recommended guidelines to use it at 19x. So you can be hitting your head against the wall trying to get all 4 corners and the center sharp at that magnification.
     
    Last edited by a moderator: Feb 21, 2012
  3. Bob-D659

    Bob-D659 Member

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    Left side numbers are inches, right side ones are cm. Center rows are magnification ratios for three different focal lengths. Just pick a pointer on the left or right side and jot the number in your notes about the print. Easy to calibrate, put a 35mm carrier in, move the head until the image is 8or 10 inches high on the baseboard, and see what points to the 8 or 10 in the column under 50.

    Edit, I just write down the cm one in my notes along with the lens I am using, sometimes. :smile:
     
  4. Helinophoto

    Helinophoto Member

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    Thank you=)

    Ok, so if I understand this correctly:

    If I raise the head with a 105 lens in it, to the "7" mark, I will be creating (roughly) a square of 42*42cm (with a 6*6 negative), meaning (6*6)*7?
     
  5. Bob-D659

    Bob-D659 Member

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    That's right.