Originally posted by AngryCorgi While I have not owned pentax cams, I have tried them at stores. I've not tried a K-7 for SR evaluation, but I have tried shooting and chimping with a K20D/18-55 kit setup in the past. I did not see acceptable results beyond 2 stops at 55mm. Can I provide "substantive evidence", no not personally as I didn't take the shots with my own card. I can point you to independent evals at independent labs that reach roughly the same conclusion. I got slightly better results with my old E-P1, but still never saw the claimed "4 stops" they tagged on the camera.
I studied that to some extent (final report is pending). The overall gain in stops thru out the range of exposure times is 2 stops for the K-7 SR. However, it has a weak spot around 1/80s where the gain
can be less and a sweet spot around 1/15s where the gain exceeds 3 stops.
VR lenses don't beat the Pentax SR around it's sweet spot or for exposure times 1/200s and less for long tele lenses. Tele VR lenses typically don't deliver more than 2 stops either.
The comment that sensor shift is inferior because not tuned to a particular FL is wrong. The rotation of a shaking camera are FL-independent. Therefore, the antishake motion is simply exactly proportional to FL.