I'm confused?????

[stoneylonesome]

A normal state of mind for me, CONFUSED ! :? :? I'm planing on buying a 1.4x or 2x tele-converter, for my 10D. I've got the Canon cheapo 28-90 4-5.6f lens and the and the 80-200 4.5-5.6f lens. Now I've heard/read that the auto features work with the converter on f4 (f4.5?) or faster lenses. Does this mean I lose my auto focus when I zoom out to say 200 and am shoting at 5.6 or 8? or do I have something confused in what they are trying to tell me. Doesn't make sense that it would only work if you apature was between f4 or f1.8. HELP!!! :D

[Scottes]

f/4 + 1.4 TC = f/5.6, the limit for AF on a 10D.

I'm not even sure that a *Canon* TC will work on those lenses - it won't fit.

Much more info: http://photography-on-the.net/forum/showthread.php?t=41922

[stoneylonesome]

f/4 + 1.4 TC = f/5.6, the limit for AF on a 10D.

I'm not even sure that a *Canon* TC will work on those lenses - it won't fit.

Much more info: http://photography-on-the.net/forum/showthread.php?t=41922

thanks I check out the link. Course they all claim that they fit just you lose some of the autofocus on some. can't belief the ads.

[Jon]

When they say that the Canon D30/D60/10D/DR/20D will only autofocus at up to f/5.6, they're referring to the lenses' maximum aperture, since the lens is always focussed wide open, and stopped down to shooting aperture only when actually taking the picture, after focus is achieved. So as long as you don't exceed a 1.4x TC on an f/4 lens or a 2x TC on an f/2.8 lens you're OK. Note, that aperture is based on your zoom's aperture at the focal length you're shooting. So your 80-200 at 200 mm is an f/5.6 max. aperture, giving you f/8 with a 1.4x or f/11 with a 2x TC - both too slow for autofocus.