>Can anyone tell me the difference between a Canon 2x converter
>and a generic 2x converter, such as Tamron or Jessops?? And the
>huge difference in price?
>This may be a silly question to some, no doubt...
>Is it something obvious such as there being a big difference
>with the quality of the optics.
>I hear the autofocus may be affected as well. Could somebody
>tell me why? I use an EOS 600 with a 75-300mm zoom.
==================
I suspect that the Canon optics are better, but I've never used a 3rd-party EF
converter.
One advantage of the 3rd party converters is that they can be fitted to most any lens,
such as your 75-300. They do not report correct aperture to the camera body, so the
camera will still *attempt* AF even when the max aperture is over f/5.6. (* attempt
AF does not mean that it will succeed)
The Canon converters are restricted to certain lenses (mostly Canon "L" series
telephotos - your 75-300 is not included) because of a protruding front element.
Canon converters generally report the correct aperture when used on the "L" lenses.
However, the "correct" max aperture (if over f/5.6) may cause the body to deny
auto-focus.
The quest for an inexpensive "600mm" lens is enticing.... but at 600mm, your lens will
have a max aperture of f/11. Autofocus will likely not work, manual focusing will be
difficult, slow shutter speeds will require a sturdy tripod and the setup will likely
result in soft images. There is a reason why pros will pay $6000+ for a 600mm/f4.0
lens...
I suggest that you purchase a 1.4X converter (a non-Canon brand, as the Canon 1.4X
won't fit either). You will lose only 1 stop (f/8.0 max aperture) and the quality
loss will be much less.
--
Dave Herzstein
[EMAIL PROTECTED]
http://www.kjsl.com/~dave
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