Ian;
Have you tried the Shake reduction for birds in flight?
I took my new K10D and Sigma 50-500 out today, but like an idiot didn't check the battery was fully charged, fortunately I'd taken my istD along and swapped the Sigma onto that, the light was all over the place, sunny one minute dark and dingy the next, I got this with the istD and the Sigma, but I cant help but wonder how much better it could have been with the K10D
Bit burned out on the right but like I said the light was all over the place.