So here's a setup that should not work - Canon 100-300mm f/4.5-5.6 USM coupled with a Kenko 1.4x DGX MC4 extender (the cheap one).
The body used was a Rebel XSi. Somehow it could focus at f/8, which is not supposed to be possible. 50D failed miserably at this, didn't try it out on the 7D yet.
EXIF should be intact on all shots. I shot in AV and shots for the most part were overexposed. Sharpening was on the heavy side so please any feedback is appreciated! The BIF shots are only so-so due to heavy cropping, lack of technique, and marginal AF.