I used to have a Canon FD 300mm F/4.0 L lens (on my Canon nF-1). It was an awesome lens. I have switched over to a Sony digital DSLR. I am now searching for a lens that can provide me with the same quality. Minolta made a 300mm f4.0 APO G. Sigma made a 300mm f4.0 APO. I have only been able to find the Sigma. Does anyone else make one for Minolta/Sony AF mount ? How good are the zoom lenses in f4.0 ? Would you suggest anything with that type of quality that won't break the bank?