I have one of the Kingslake books on optics but at this url there is a very good explanation of COC. http://www.cs.berkeley.edu/~qtluong/photography/lf/fstop.html Peter K * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
