For me as a newbie this is the most difficult thing to do birding and the most fun...ESPECIALLY when you start editing and see that it was a success. In the 2.2 seconds that the D850 fired off 20 frames it NAILED this raptor and later the bream every frame ...D850/Sigma CONTEMPORARY hand held. (couldn't have done this with a F4 prime zoom)...GET THE FEVER FOR BIRDS IN FLIGHT!!