First of all: thanks for all the replies so far! I'd like to throw a few tidbits into the discussion. First of all, I know quite well how focal length scales with film format and have used a vast variety of focal lengths on my EOS 3, from 14mm to 1300mm to be accurate. The difference in use between the 50mm and the 65mm is, from what I have seen in the flickr examples, much more than the difference in focal length seems to suggest. There seems to be a discontinuity in perspective perception between these two, from basically normal perspective with the 65 to pronounced wide angle perspective with the 50. The images taken with the 50 look like my EOS 3 images taken with the 14mm, maybe a little less extreme, but conceptually in the same ball park. The images taken with the 65 on the other side seem to be a completely different animal and remind me more of normal focal length than of wide angle.

There are different ways of explaining this (and none of my efforts may actually be correct).
  • It could be that anyone who really wants to achieve a wide angle perspective just doesn't bother with the 65 but uses the 50, whereas if one just wants a slightly wider frame one would go for the 65. Note that how perspective is perceived depends a lot on framing and composition, if I don't include foreground elements even my 14mm lens doesn't look so unusual.
  • For a while the 50mm was said to have more optical problems than the 65 so I could imagine people used the 50 only if they really wanted to have a pronounced wide perspective. This may have led to disproportionally many 50mm images with "in your face" wide angle perspective whereas the 65mm images are more mixed.
  • Or is it that our eyes (which don't have a well defined field of view, the image just gets more blurry further off axis) barely accept the 65mm perspective as "normal" whereas the 50mm perspective deviates just a tick too far from our normal viewing habits?
  • Or do I see a huge difference where there really is just a slight one?