The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 4.5mm F2.8 EX DC HSM Fisheye and the Canon 17-40mm f4.0L 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 17-40mm f4.0L USM is the longer of the two lenses at 97mm. The Sigma 4.5mm F2.8 EX DC HSM Fisheye with a length of 78mm, is 19mm shorter. Besides being longer, the Canon 17-40mm f4.0L USM also has a larger diameter of 84mm compared to the Sigma 4.5mm F2.8 EX DC HSM Fisheye's 76mm 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 4.5mm F2.8 EX DC HSM Fisheye weighs 470g, which means it is 30g (6%) lighter than the Canon 17-40mm f4.0L USM which has a weight of 500g.
Lens Mounts
Both the Sigma 4.5mm F2.8 EX DC HSM Fisheye and the Canon 17-40mm f4.0L 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 4.5mm F2.8 EX DC HSM Fisheye is also available in the Sigma SA and Nikon F (DX) mounts.
Focal Range
Sigma 4.5mm F2.8 EX DC HSM Fisheye is a prime lens with fixed focal lenght of 5mm which has an effective (full-frame 35mm equivalent) focal range of
8mm when used on a APS-C / DX format camera.
On the other hand, the Canon 17-40mm f4.0L USM has a focal range of 17-40mm and 2.4X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 27.2 - 64mm.
