Archived posting to the Leica Users Group, 2001/02/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]on 2/8/01 12:31 PM, Austin Franklin at austin@darkroom.com wrote: >> No, with respect, you're not addressing my point, Austin. DOF >> as commonly >> used (eg in published DOF tables, lens engravings and >> published formulae) >> refers to DOF of an image at a particular nominal >> magnification and has for >> fifty years. Your definition doesn't. > > I believe DOF (ie, engraved on a lense) is referenced to the film, not to > any magnification. The CoC for a given film format, which is a fundamental part of the DOF equation, is derived from the expected degree of magnification, which is (IIRC) 8x for 35mm. It's a simple matter to work up a DOF calculator based on the standard equaltions which derives the CoC value from a degree of magnification you specify. A glance at the derivation would tell you this. - -- Johnny Deadman http://www.pinkheadedbug.com