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  1. #1
    ChrisW's Avatar
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    Lens For High Acutance Large Prints

    I commonly print images up to 40 inches using a Besseler 23 IIIC condenser and Rodagon 80mm off b+w 120 25 iso films. The distance form lens to floor easel is 76 inches. The acutance is good, but at these enlargements should I get a different lens? 4x5 format would help, but for mobility I must shoot 120.

    Also, am I correct in assuming an aperture of f11 will produce the sharpest image? Film flatness in not an issue as I use a double glass carrier.

  2. #2
    rbarker's Avatar
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    Assuming you have the f/4 80mm Rodagon, it's a 6-element lens with 4 groups - one of the better "standard" designs, optimized for 2x-10x (6x optimum) magnification (manufacturer specs). You might get improved results with one of the APO enlarging lenses. The 80mm f4 APO Rodagon, for example, has a (stated) magnification range of 2x-15x (10x optimum).

    As to the sharpest f-stop, that's usually 2 or 3 stops down from wide open, but running your own tests will show what your optimum f-stop is.
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

  3. #3

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    I would expect a first class enlarging lens for the 120 formats to be at optimum by f8 perhaps by f5.6
    Claire (Ms Anne Thrope is in the darkroom)

  4. #4
    ChrisW's Avatar
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    Ralph, thanks for the advice. I will get an APO lens. Any thoughts on Rodenstock versus Schneider?

  5. #5
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    I have a Schneider Apo-Componon 90 mm lens that I use for 6x7 negatives. It is extremely sharp up to my maximum print size of 20 x 24.
    Jerold Harter MD

  6. #6
    ChrisW's Avatar
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    Ms. Thrope:

    Thanks for the guidance. In my infinite wisdom I only tested f4, f11, and f22. Perhaps I should have listened during my physics class.

  7. #7
    df cardwell's Avatar
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    Each lens is DESIGNED for a specific job. Hunt down a Rodagon G, designed for really big prints, unlike the apo componons and Rodagon n

    If you come upon a 105 apo el nikkor, get it.

    For getting the most from the lens you have,
    lay a mirror on the edge of the print and stop down until you see a clear aperture. It may be a stop or stop and a half from wide open.

    Go no further.
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  8. #8
    ChrisW's Avatar
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    Will the 105mm focal length work with 6x6? Is the Nikkor better than either Rodenstock or Schneider? Will Speed marry Trixie?

  9. #9
    df cardwell's Avatar
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    Even though you'll need to stop down to f/8, the 105 Apo El Nikkor will be fine. It is head and shoulders above anything. And priced accordingly. But some turn up when color sep houses close, or top labs unload stuff. The downside is the cost. Some are available, still, new. Slightly under $3k.

    Speed would be a fool to let Trixie go.

    .
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  10. #10
    ChrisW's Avatar
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    Quote Originally Posted by df cardwell
    For getting the most from the lens you have,
    lay a mirror on the edge of the print and stop down until you see a clear aperture. It may be a stop or stop and a half from wide open.

    Go no further.
    Neat trick with the mirror. I assume a clear aperture is when all leaves are showing. This is a different aperture depending on the magnification. Hence the range of 5.6 to 8 as proffered by Ralph and Claire. All these years I thought f11 to be the optimal due to my flawed logic. Thanks.

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