> And I understand that with my A2 I
> would not have AF. How do they effect metering? How about
maintaining the
> lens IS function? Anything else I should know about these to help me
decide?
I have both extenders and the 100-400 IS lens. IS does continue to work
with either (or both), but AF will not work with your camera. I'm in
the same boat because I use an Elan IIe. AF will work only if you use
the 1.4x with an EOS-3 or EOS-1V.
Both extenders decrease sharpness and hand-holdability. If you're
hand-holding the lens (as I always do) you'll need to use film that's
about 2 stops faster than normal with the 1.4x extender to compensate
for the longer focal length and smaller aperture. The 2x extender would
require 3-4 stops faster film. So, as a rule of thumb, I use ISO100
film when I use the 100-400 alone, and ISO400 film when I use the 1.4x
extender. Naturally, the faster film further degrades image quality.
Here's an example photo taken with the 2X extender and the 100-400IS
lens (at 400mm), handheld at f/11 and (around) 1/100sec., with 400 speed
film (the URL may wrap to two lines):
http://www.northrup.org/photos/noframes-high/cruise/Day10-Barcelona-Spai
n/imagepages/image4.htm
This is typical of the results I see--no visible camera shake, but not
sharp. The graininess demonstrates that I had to use a faster film to
get an acceptable shutterspeed--you could always use a tripod.
Tony Northrup
http://www.northrup.org/photos/
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