The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 14-24mm F2.8 DG HSM and the Canon 15mm f2.8 Fisheye for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Sigma 14-24mm F2.8 DG HSM is the longer of the two lenses at 135mm. The Canon 15mm f2.8 Fisheye with a length of 62mm, is 73mm shorter. Besides being longer, the Sigma 14-24mm F2.8 DG HSM also has a larger diameter of 96mm compared to the Canon 15mm f2.8 Fisheye's 73mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Canon 15mm f2.8 Fisheye weighs 330g, 71% (820g) lighter than the Sigma 14-24mm F2.8 DG HSM's weight of 1150g.
Lens Mounts
Both the Sigma 14-24mm F2.8 DG HSM and the Canon 15mm f2.8 Fisheye has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K.
Sigma 14-24mm F2.8 DG HSM is also available in the Nikon F (FX) and Sigma SA mounts.
Focal Range
Sigma 14-24mm F2.8 DG HSM has a focal range of 14-24mm and
1.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
22.4 - 38.4mm.
On the other hand, the Canon 15mm f2.8 Fisheye is a prime lens with fixed focal lenght of 15mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 24mm.