I have one on a Nikon. I’ve read a few articles on this lens and the advice is not using it at its fullest range because the image will be quite soft. Use a monopod to avoid blurred pictures and if handheld use a shutter speed of 1/focal lenght your are using for the shot. It’s a beautiful lens and since you have a DX sensor you get the equivalent of a 900mm on a full frame camera because of the cropping efect on your sensor.

use 2 to 3 stops exposure compensation against a bright sky. The sky will be blown out but your bird should look good.