BobT wrote: Julian where *all* these calculations really break down (especially when trying to prove finer points) is that the manufacturers "economy with the truth" hides from you the data you really need to know. But it is for your own benefit: auto-everything cameras do it all for you, no? <snip> Oh, I use Microsoft Excel for Optical Calculations. Can't beat it for flexibility ... BobT _____________________________________________________________________________ Would anybody know of a calculator that allows to combine several elements, i.g. lens + extension tube / lens + extension + converter? Kai * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
