There are lots of reviews of these matters on photo.net. You might
want to look there. This list has a great diversity of platform
users, with some very unique experience. But wide experience about
one platform and all its products, I wouldn't expect to find that
here.
Just last night I found a fine and useful artcle about Canon
extenders on photo.net, with good examples of how much degradation
one can get with them.
And if Canon's autofocus doesn't work below f4.5 I'd be amazed.
Especially since I spent three hours this summer shooting next to
someone who had an f2 70-200 with 1.4x extender and was making a
living shooting with it - one on each of two Mark II bodies, to boot.
He wasn't manually focussing. He didn't have time.
--
Emily L. Ferguson
mailto:elf@xxxxxxxx
508-563-6822
New England landscapes, wooden boats and races, press photography
http://www.vsu.cape.com/~elf/
