Our verdict
The Canon EF 8-15mm f/4L Fisheye USM remains a slight oddity and yet an extremely fun lens to use. The optical quality is impressive for such a wide lens and the performance is exceptional, from the autofocus to the weather-sealing.
For full-frame users, having the combination of a circular and full-frame fisheye in one optic will no doubt be appealing, although its use is limited by the subjects it will suit and the novelty of severe distortion can wear thin over time. APS-C users and, in some respects, APS-H users (EOS-1D range) are provided with a far less extreme effect and therefore a more widely usable lens.
The results still contain rather severe distortion, however, so remain suited to dynamic scenes and would need heavy lens correction for any landscape or architectural shooting.
Those seeking a controlled lens for APS-C should probably opt for the less expensive Sigma 8-16mm model, but those looking for extreme effects on both APS-C and, particularly, full-frame will really enjoy the possibilities this Canon lens has to offer.
