Et voila...
I have been able this morning to take a walk at minus 20c for about an hour to play with the 50-500mm around the area.
First thing ... i made the mistake to check my sensor A900 just before to go outside ... My 10 first shots was totally blurred, i opened the camera and put it on cleaning mode (yes outside in the snow ... , i like dangerous situation ... ). The sensor was totally fogged, but a few second and the outside cold make the humidity disappear. Result, the sun helped me to discovered that my sensor is dirty like garbage

. Seriously i will have to clean it. But ... i have decided that i will continue the shooting.
I have had to processed all the pictures in Lightroom to removed the spots. (i will say ugly hair forms and other things ... ).
I have took all the picture in cRaw, processed it in lightroom, after that exported it jpeg 95%, and reduced it at 75% sized with faststone viewer.
Here is the link :
http://www.pbase.com/nadeauf/bigmaa900
Observation with the Bigma on A900 :
- 50 to 330mm very good
- 330-400mm good and start to do little vignetting
- 500mm, impressive, but not as good under 400mm, there is evidence of vignetting in some shot (but easily corrected in lightroom)
- 500mm f6.3, usable, but i preferred to stop down to 7.1, and almost 8.0 (probably because i wanted to compare almost all my shot with my sold before xmas 800mm Sony Reflex, need money to buy other lens

)
I have shot all at ISO 200, except my 10 lasts pictures (there are not yet on pbase). I have found that i need to gain faith in the ISO800 for outside photography with this kind of lens. Because in good light the result is very good. I was stupid to stay at ISO 200 all the morning ... but i will know next time.
But for the ISO200, the SSS of the Sony do a good job. I was shooting in High Speed Drive, and taking almost of the time 3-4 shot for a same subject, and at 500mm and under dangerous situation (like 1/200 and less) a good 75% of good shot in the series. Probably the weight of the lens help.
I have not done any scientific test there ... they are feeling and observation (Regression testing if for my day job

not my hobby sorry).
Hope this will help to you discover this lens beast

.
See you next week, I'm in the plane for San Jose tomorrow morning. (thinking if I'm bringing my A700+ 18-200mm , or my Fuji F30 ... ).
Regards,
Frank