03-12-2015 05:25 PM
You see zooms that go to 55mm, but 55mm primes (slang for non-zoom lenses) are kinda rare these days. 50mm has always been the full-frame standard lens and still is. Legend has it that the 55mm, and its cousin the 58mm, were designed to accommodate early film SLRs because a slightly longer lens was easier to keep out of the way of the mirror. When they figured out how to make a 50mm lens and mirror assembly that would stay out of each other's way, the other two focal lengths went into decline.
03-12-2015 07:52 PM
03-13-2015 10:43 AM
You would really have to look and pay attention to tell the difference between a shot with a 50mm and a 55mm.
Probably lees than 3 degrees if I remember correctly. I had one, still do, back in the film days.
Sony has a 55mm f1.8 from Carl Zeiss for the A7, I think, and there may be an adapter to EF. I would avoid this, however, and just get the EF 50mm f1.4.