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Old Feb 23, 2006, 3:19 PM   #1
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Join Date: Feb 2006
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I'm considering getting the Extender EF 2x II, but I don't know anything about it. Seems like a cheap way to get twice as much length, but I don't know if it's too good to be true. Their website says

With the EF 2x II, AF is possible with any EOS body if the lens has an f/2.8 or faster maximum aperture

Does this mean that AF only works if you're at 2.8 or faster, or AF doesn't work at any aperture with this if your lens doesn't have a max of 2.8?

Also, can anybody comment on the picture quality when it's used?
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Old Feb 23, 2006, 4:02 PM   #2
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The autofocus is camera and lens combo dependent. the canon 1 series cameras will autofocus at f/8. the 20d/30d will autofocus at f/5.6 or faster. so, if you have a 20D and have a f/2.8 lens on it adding the 2X TC will still autofocus but probably much slower. If you have a 1 series camera you can put an f/4 lense on it and autofocus with the 2X TC. From what I have heard/read the 2X TC does cause a noticeable loss in image quality. With excellent quality lenses (L glass) the loss is not as greatly noticeable. If you don't mind manually focussing, you can use the 2X TC on any camera. Another thing is that any TC (1.4X or 2X) does not work very well or as well on zooms as they do on primes. hope that helps.

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