Yep I really did! First a 100% crop from a shot taken with a 70-200mm f2.8 IS L M2 1/200sec, ISO 100, f8 - flash used to aid lighting And now from the 800mm 1/200sec, ISO 100, f8* - flash used to aid lighting Ok so not that amazing in subjects (its two books!) but each of those shots only went through RAW processing in defaults and only AAcountering sharpening was applied (ie standard same to both). For straight out of the camera the performance at 800mm (which as you've probably guessed is a pair of 2*TCs (sigma and canon M2) on the 70-200mm) is surprisingly good. Granted this is closer ranged stuff and its performance at distance might well suffer more significantly, but still its far and above what I'd expect with two TCs. I might actually try it properly in the field with a 2*TC and a 1.4TC and see how it goes. * f8 on the camera, but one TC is not reporting to the camera so chances are its two stops down from there already - so yes not ideal for high shutter speed work with 4 stops of light lost.