http://www.pbase.com/liquidstone/7d_preprod


- Yes, this had a Canon 1.4x TC. I did stop the combo down to f/7.1 to improve DOF and sharpness. A wide open 500 f4 IS + 1.4x seems to be pushed to its limit by the high pixel density.

- I can confirm that the pre-prod 7D's AF works on the following.
1. Sigmonster (Sigma 300-800 DG)
2. Sigma 18-200 OS (OS operates as expected too)
3. Sigma 10-20
4. Sigma 24 1.8 DG macro

- Also, the center point can lock focus on contrasty subjects with an unwired Tamron 1.4x TC + 100-400 at full zoom (560 mm, f/8 ). AF is slow and hunting, but I'd say it's much better than my 40D in this particular set-up, and similar to my 20D.