Sigma 10mm f/2.8 Fisheye, Sigma 4.5mm f/2.8 Circular Fisheye, Sigma 12-24 EX DG. Click here to enlarge.
Few weeks ago I have reviewed the Sigma 15 and Sigma 8mm Fisheye
, two fisheyes for fullframe cameras. Unlike all other lenses, fisheyes don't try to correct the distortion, so they can achieve an amazing angle of view of 180 degrees (or even more, in some cases)! Until few years ago, if you had an APS-C camera, there was no way to get a real fisheye effect: there weren't fisheyes for the APS-C format, so you had to use fullframe fisheyes, that gave "just" an angle of view of 120 degrees, due to the 1.5x multiplier.
In 2003, Nikon announced the Nikkor 10.5mm, the first fisheye designed exclusively for APS-C cameras: a great news for Nikon users, but for years Canon, Sony and other brands users have had little of no options. In 2007, Sigma announced its first APS-C fisheyes, the 10mm (diagonal fisheye) and the 4.5mm (circular fisheye).
In comparison with their fullframe equivalent, the 15mm and 8mm, the new APS-C fisheye have clear improvements: the built quality is even better - they are on par with the Canon L lenses, except for weather sealing - and they have the ultrasonic AF motor, with full time manual focus. The AF is so fast that it seems almost istantaneous! Moreover, they have a very short minimum focussing distance, just 13.5 centimeters from the sensor: it means that you can get in sharp focus an object places at 2-3 centimeters from the lens!
As you can imagine, these lenses are great for creative purposes - they have an exaggerate depth of field, they create a very peculiar distortion and, thanks to their good macro ratio, they can be used even for macro photos of small subject into their environment.
Specifications (compared with the FF Fisheyes)