Comment Re:Canon or Nikon (Score 1) 569
F-mount (for Nikon) and K-mount (for Pentax) are indeed very old mount; these two companies did a very good job for preserving backward compatibilities while adding new features to the newer lenses. K-mount is about 30-40 years old while F-mount dated back to the late 50s. Even so some higher-end cameras can get AE with the old lenses without electronic contacts!
Canon current EF-mount is a lot younger. They created the EF-mount in the 80s, which is incompatible to their old line of lenses. Though so Canon they produces a lot of EF-lenses nowadays so you would find it abundant on the market.