I have an EOS Elan IIe. I recently bought Canon's 75-300 MM Ultrasonic/Image Stabilizer, and the Canon EF 2XII Extender. However, Canon says the Extender is not compatible with the lens (and that's true, the lens won't focus with the Extender on it). Does anyone know if there is an Extender that is compatible with the Cannon 75-300 lens I have?

-- Tracy Truman (tracytruman@hotmail.com), April 05, 2001

Answers

Hi, I think the problem is more caused by the lens rather than the 2X converter. The 75-300 is a f4-f5.6 (max aperture). With the 2X it's becoming a 150-600mm f8-f11 and the autofocus does not work at smaller aperture than f5.6 (except for the EOS 3, at f8).

I think that some third party converter dont "tell" the camera that the aperture become smaller than 5.6, but i'm not sure. Anyway, i don't think that the autofocus had sufficient light to be efficient.

-- Pascal Harvey (harveypascal@hotmail.com), April 05, 2001.

Canon's TC's only work on some telephoto lenses, mostly, if not only, "L" class lenses. In fact they extend so far forward of the lens mount that some lens's rear elements can be damaged if you use them.

As far as I know, all non-Canon brand TC's can be used with the 75- 300 IS. And none of them report to the camera that they are being used. So even though the effective aperture is smaller than Canon's minimum requirements (f/5.6 for the Elan IIe), the camera will try to autofocus. It probably wont be able to with a 2X though since the effective aperture will be f/11. Way too small.

You can usually get away with using a 1.4X TC since the effective aperture will be f/8 and, in spite of Canon's specs, it will AF in moderate light/contrast.

I use a Kenko 1.5X TC with this same lens.

-- Jim Strutz (j.strutz@gci.net), April 05, 2001.