John, Thanks for your detailed reviews of TCs. When someone takes the time to share his test results in such detail, it spares list members like me from wasting money on turkeys.
But my question about "effective aperture" remains unanswered. It's clear enough that by multiplying the focal length, you reduce depth of field. I'm asking this: Given that a 1.4X reduces depth of field, do you get some of it back because your lens's f/5.6 setting is now effectively f/8? John Mustarde <[EMAIL PROTECTED]> wrote: You get less DOF when adding a TC, assuming the lens-with-TC and the same bare lens are both wide open and focused on a subject the same distance away. So a 300/2.8 + 1.4X TC = 420mm/f4, focused at 21 feet will have less DOF than a bare 300/2.8 focused the same 21 feet distance. 13 Selby Court Poolesville, Maryland 20837-2410 [EMAIL PROTECTED] H (301) 349-5243 - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
