I had two Sony models, I forget which ones (Alpha?), they were top of the line at the time. I loved them. But I ultimately moved to Nikon. I now use a Nikon D610 and my nature lens has been an 80-400mm zoom. I just bought a 200-500mm zoom and have yet to give it a good tryout. I can't imagine a 600mm one! My 500mm is REALLY heavy, I think I need to work with some weights to build up my forearm strength (I'm 70)... Aside from playing with shots of moving water, I shoot all handheld. I have a large selection of lenses, macro, a great wide angle, some others. I like Sigma lenses but other than browsing those now and then, I stick with Nikkor.

My dad was a photographer (not quite professional) and my brother currently owns a camera shop/photo lab. Kind of runs in the family I guess!