> "Daniel Flather" <[EMAIL PROTECTED]> wrote: > 1) With a tube can a lens (100/2) still be focused throughout > it's entire range? > 2) Same question but with a 500D?
Yes and Yes. and No and No. Clarification: Without any accessories, a lens can be set to focus between its CLOSE FOCUS distance and INFINITY, as marked on its distance scale. In general with either a tube or a diopter, the lens can still be set to focus within these two extremes ON ITS DISTANCE SCALE, but the ACTUAL focus distance will be much closer. An example: EF 50mm f/1.8 focusses between CLOSE: 0.25m (mag = 0.25x) and FAR: infinity (mag = 0) EF 50mm f/1.8 with 12mm extension tube focusses between CLOSE: 0.152m (mag = 0.49x) and FAR: 0.258m (mag = 0.24x) How much closer? What if you use different combinations of EXTENSION, DIOPTER and TELECONVERTER? Solution: Use the lens calculator: http://members.home.net/jul.loke/ Note than in some cases too much extension on a wide angle lens set at certain focus distances will result in the plane of sharp focus within the lens itself! Cheers Julian Loke * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
