I just picked up a Takumar 500mm f4.5 for $200. This lens was probably built in the late 60s. From what I can find on-line it suffers from low contrast and moderate chromatic aberration. It has a nice big hood. Due to the size, filters can only be mounted on the rear. I have a nice strong tripod for it.

I realize I'm not going to get results like a modern $10K lens, but does anyone with experience have any thoughts on maximizing performance here?