>> to be 74.5mm > ........measured from where to where?
That's the focal length - if you set the lens for 1:1 and used it to focus light from infinity, the rear nodal point should be 74.5mm from the film plane. For a telephoto design, this could be outside the physical lens itself (but not for the 100mm USM Macro :-) Why is focal length important? At a fixed magnification (e.g. 1:1), the focal length determines the working distance and the field of view. Cheers Julian Loke * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
