The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 10-20mm F4-5.6 EX DC HSM and the Canon 8-15mm f4L Fisheye USM 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. Canon 8-15mm f4L Fisheye USM is the longer of the two lenses at 83mm. The Sigma 10-20mm F4-5.6 EX DC HSM with a length of 81mm, is 2mm shorter. On the other hand, the Sigma 10-20mm F4-5.6 EX DC HSM has a larger diameter of 84mm compared to the Canon 8-15mm f4L Fisheye USM's 79mm 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. Sigma 10-20mm F4-5.6 EX DC HSM weighs 470g, which means it is 70g (12%) lighter than the Canon 8-15mm f4L Fisheye USM which has a weight of 540g.
Below you can find the dimension and weight table of the Wideangle Zoom Lenses in Canon EF Mount for size comparison purposes.
Ultra-Wideangle Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both the Sigma 10-20mm F4-5.6 EX DC HSM and the Canon 8-15mm f4L Fisheye USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon T8i, Canon 90D and Canon SL3.
Sigma 10-20mm F4-5.6 EX DC HSM is also available in the Four Thirds , Pentax KAF, Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Sigma 10-20mm F4-5.6 EX DC HSM has a focal range of 10-20mm and
2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
16-32mm when used on a APS-C / DX format camera.
On the other hand, the Canon 8-15mm f4L Fisheye USM has a focal range of 8-15mm and 1.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 12.8 - 24mm.