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  1. #11

    Join Date
    Apr 2003
    Posts
    134
    If one standard on your camera is in a fixed position, you could use the calculators some of the others have referered to to calculate the hyperfocal distance, then use the basic optical equation (1/f = 1/do + 1/di) to convert the hyperfocal distance to a image distance -- lens to film. For accuracy, focus the lens at infinity, then measure how many mm farther out the lens should be to focus on the hyperfocal distance.

    If you have enough time, I find the technique of focusing on the desired near and far points, measuring the spread in position of the standard at the two focus points, resetting the focus to the mid-point and then setting the aperture according to the focus spread works very well. The method is explained at " How to select the f-stop" at http://www.largeformatphotography.info/fstop.html

  2. #12

    Join Date
    Sep 2002
    Location
    France
    Shooter
    Multi Format
    Posts
    357
    Quote Originally Posted by bmac
    Would the COF for 8x10 be 4x that of 4x5?
    Biran,

    standard-COF is format_diagonal / 1500 - at least is this the one that is used to calculate most DOF-scales on lenses. However, this is a rather old convention (dates back to WW II) and film quality is much better today. For larger prints and/or more sharpness use anything between 1000 and 1300. However, an even smaller COF will unnecessarily decrease your DOF.

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