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  1. Converting focus spread in feet to lens change(MM)

    In response to Pete Andrews the treatises presented by Hansma, Peterson, Luong et al derive the optimum F-Stop for a given focus spread. The formula is simply fs=(Focus spread * 375) ^ 1/2 . For a...
  2. Converting focus spread in feet to lens change(MM)

    The Sinar has a scale on the rail which is calibrated to approximately 1 mark to 1.2 millimeters. Thus, a Sinar spread of 10 equals 12 millimeteers. The scale is not in millimeters because Sinar...
  3. Converting focus spread in feet to lens change(MM)

    Thanks for the responses. The formula for the focus spread is FS=(1/(1/F-1/VN))-(1/(1/F-1/VF)) from p.l. Andrews, where VN = near distance,VF = far distance, and F = focal length of the lens. This...
  4. Converting focus spread in feet to lens change(MM)

    Is there a formula for a specified focal length lens which will convert the focus spread of the subject planes, in feet, to the focus spread for the lens, in millimeters?? This would be for a...
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