Pros:
all-purpose fisheye, perfect for all detector types available in the Canon system,
solid and shapely casing,
sensational image quality in the centre of field of view,
good or decent image quality on the edge of the field,
relatively well-corrected coma,
negligible astigmatism,
good work against bright light,
silent, efficient and accurate autofocus.
Cons:
chromatic aberration momentarily a bit too high.
The Canon EF 8–15 mm f/4 L Fisheye USM is one of few lenses in which case I had problems what to put into the “cons” section. A bit by force I decided to mention the chromatic aberration problems. I say “by force” because most of the time it is corrected averagely well and, compared to other “fisheye” constructions, the Canon fares rather well here. Apart from splendid optical properties you should appreciate the versatility of this lens. Canon is the only manufacturer which offers reflex cameras with three different sensor sizes. Launching this lens they made sure all the users will have a fisheye tool, no matter what sensor they work with. What’s interesting, the owners of APS-H matrix reflex cameras benefited the most from this move – finally they have a diagonal fisheye lens which can be attached to an APS-H body.