I'm trying to decide between these two lenses.


400mm is almost 2 inches shorter, lighter, and has the 77mm filter thread (which I have a good number of).


500mm is obviously longer and I'm guessing will take better pictures at 400mm, but is longer, heavier and doesn't share a filter size with any of my current lenses.


Anyone have any first-hand experience with them?


(I would love to get a Canon 100-400 L, but I don't know if I can justify the cost... I'm more of a hobbiest at the moment).