bluedubius
Rick
Playing some more with lens combinations. After a number of tests with different configurations, I find that stacking the Kiron 2X teleconverter with a GSO 2X barlow gives me the overall best results. The images from this combination are even slightly better than I can get from the GSO 2X barlow alone. I still don't know how to explain this, even though I have seen people in other forums getting similar results when stacking teleconverters. This configuration gives me a working focal length of 2400mm and factoring in the 1.5x crop factor for the Fuji S2 Pro, that's 3600mm and still getting good detail (although I'm down to around 1/180 sec shutter speed at 400 ISO). I think this is going to be my working combo for those distant raptors.
Rick
Rick