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  1. #21
    RalphLambrecht's Avatar
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    the nice thing about working with cocs s that the enlargement factor does not play a role any longer.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  2. #22
    RalphLambrecht's Avatar
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    viewing distance and print size cancel each other out and are no longer varibles if a coc is uded.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  3. #23
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    In his book Post Exposure Ctein suggests that "adequately sharp" (meaning, it appear sharp when viewed alone) requires about 5 lp/mm on an 8x10 print, but that "perfectly sharp" (meaning no difference is visible in side-by-side comparisons if sharpness is increased further) requires about 30 lp/mm! On an uncropped 35mm negative (enlargement factor 7) this corresponds to CoC diameters of about 0.014 mm and 0.002 mm respectively, but the latter is not achievable due to film, lens sharpness and DOF limitations. For "adequately sharp", an aperture of f/16 should give an airy (diffraction) disk diameter of around 0.014mm.

    My own inclination is to retain diffraction sharpness and compromise DOF if necessary since I can adjust the focus distance to ensure that the aspects of the scene that I consider most important - typically those closest to the camera - are as sharp as possible, while allowing some loss of sharpness for (due to DOF limitations) in other areas. If you start to lose sharpness due to diffraction, then this affects everything in the photograph, which I find the worse of the two evils.
    Last edited by andrew.roos; 04-04-2012 at 03:16 PM. Click to view previous post history.

  4. #24

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    An interesting read on the subject can be found here....
    http://www.normankoren.com/Tutorials/MTF6.html

    Enjoy!
    Anyone can make a Digital print, but only a photographer can make a photograph.

  5. #25
    RalphLambrecht's Avatar
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    Michael,I have a must-read for you on this topicbut it's too big for APUG.please send me a n email to rlambrec@ymail.com.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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