SeilerBird said:One important consideration when choosing a system is Image Stabilization. The Tamron 200-500 does not have IS built in. Sony builds IS into the body, Nikon and Canon build IS into the lenses.
Very good point Tom. Shooting aircraft in flight, like birds, pretty much requires hand held and also with prop aircraft a relatively slow shutter speed to keep from 'freezing' the prop ... jets are easy in that regard ... high shutter speed works well.
thanks,
Howard