I'm looking for a fish eye lens to use with my 5d.
The alternatives I can see are canon 8-15L f/4 and canon 15 f/2.8.
Canon 15mm is a prime and it has a faster aperture, while 8-15 is an L lens.
The way I understand the matter, there's little advantage to having fish eye zoom on a full frame body (besides making semi circular pictures all the way down to 8), and the zoom was invented to help the users of cropped sensors.
Did anyone compare the two side by side? Which one gives sharper/better picture quality? Is there anything else that I should mind about fish eye lenses?