Which 2x Teleconverter for Canon 100mm

I currently have run the 1.4 Kenko TC on the 100mm Canon lens on a 20D but want to try the 2x teleconverter.

Which one should I consider, Canon or Kenko?

Has anyone tried a 2x and, which one. I see limitation in AF on the Canon version of thge Teleconverter and that it does not list the 100mm in the compatibility chart. The Kenko version seems to just indicate that anything F2.8 or wider for lenses is appropriate.

Any thoughts are appreciated

Todd

Hey Todd -

I could've sworn I've mentioned something about this before, but I can't find my own post in a search, so maybe not.

Either way, one issue with using the Canon 2x TC with the 100mm macro is that it won't work. That is, it won't physically fit together unless you also add a 15mm (or 25mm) extension tube between the TC and the lens.

The Kenko TCs don't seem to exhibit this problem, but they do caution that you may have intermittent AF issues with the 100mm macro lens (similar to their 1.4x TC...it's somewhere in the manual).

That may be why the 100mm is not listed in compatible lenses. I have noticed the odd issue with the 1.4. As you know, with USM you can still switch to manual focus should this happen. That and I would most likely be shooting that set-up manual.

Thanks for the insight.

I have felt the Kenko glass is fine on the 1.4 for what I can see, anyone have the same experience with the 2x?

The Canon indeed won't fit the 100mm lens - only certain of the L lenses - because it's got a protrusion that sticks out INTO the lens...

Interestingly enough, I just used a Kenko 2X TC with my 100mm for the first time last week on a trip to Belize. I didn't expect it to AF, but was pleasantly surprised when it did - reasonably well, in fact (provided there was enough light). Bear in mind that I was using it on a 1DsMkII, which is full frame, so I can't guarantee that it'll AF as well (or at all) on a 20D. But you'll find out pretty quick if you try it.

If it turns out that it WON'T AF, the problem with planning to use MF is that your MF ring may not fit over the TC, meaning you may or may not actually be able to use MF (my Seacam MF ring for the 100mm will NOT work with the TC, which is larger diameter than the 100mm lens).

FWIW, here was the best shot I got with the 2XTC and 100mm (an arrow blenny):