I recently sold my version II 2X teleconverter and purchased version III after reading numerous reviews about how much better it was in terms of sharpness and IQ.

This Goldfinch was in a shaded spot in an oak tree in my front yard probably 50 feet away, to me, the image looks pretty darn good considering it was relatively poor light and slow SS, what say you all?

1D MIV
500mm f/4l + 2X TC III
Tripod
ISO 1000
f/8
1/80
manual mode, evaluative metering
580 EXII + Better Beamer ETTL -2 1/3
Only the center AF works at f/8