I have an opportunity to pick up a canon 600mm f/4/5 fd manual focus lens. Fd to Eos converter included. I intend to use it for wildlife. Can anyone guide me as to what to expect both from a performance and price perspective? I know price is hard to determine, but I have searched the net and come up empty on price or even a review of this lens.

I used this lens a lot about 20 years ago. It was not a very sharp lens wide open; it's not an L series which are sharp even wide open. I suspect a modern 300 with doubler would be sharper.

Thank you Nick. I did a search on this forum and found a little more info concerning the adapter. The fact that it is optical along with your information suggests the combination is not for me. Thanks again.