Circular, yes if you look at it from a different perspective but rectangular looking at this angle. Caught this guy with his big ol' honking lens, shot with my big ol' honkin' lens. He was looking for a Falcon he saw, very rare in our area. I looked too but didn't see it. We compared images and talked for a while. Nothing like talking to another photographer using the same equipment as you. However, I have a battery pack on my camera so that was the only difference.

Completely straight out of the camera. No nothing done to this image...hehe!