Those are excellent shots of the hawk. I see them all the time here but always hovering around farm land. They are never in area that is accessible it seems.
A Great Blue Heron from yesterday with the Sigma 50-500 on the K3. ISO 2500, 1/1000s, f10
This one was not moving an inch so I dropped my shutter speed and ISO down, ISO 640, F11, 1/400s.
I tried out the 1.7 AFA converter that I recently purchased here in the Marketplace on the 60-250. Definitely different than shooting with the Bigma. I really can not tell too much difference between the two even though the 60-250 is only 425mm with the 1.7 AFA on.
I forgot to change from my Sigma 50-500user setting on the k3 so I was shooting at high f stops. f11, ISO 200, 1320s. Next time I will need to open the lens up more.