The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 10-20mm F3.5 EX DC HSM and the Canon 20mm f2.8 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. Sigma 10-20mm F3.5 EX DC HSM is the longer of the two lenses at 88mm. The Canon 20mm f2.8 USM with a length of 71mm, is 17mm shorter. Besides being longer, the Sigma 10-20mm F3.5 EX DC HSM also has a larger diameter of 87mm compared to the Canon 20mm f2.8 USM's 78mm 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 20mm f2.8 USM weighs 405g, 22% (115g) lighter than the Sigma 10-20mm F3.5 EX DC HSM's weight of 520g.
Filter Threads
The Sigma 10-20mm F3.5 EX DC HSM has a filter size of 82mm whereas the Canon 20mm f2.8 USM has a 72mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 82mm filters that we recommend you to consider for the Sigma 10-20mm F3.5 EX DC HSM:
And these are the 72mm filters that we recommend for the Canon 20mm f2.8 USM:
Lens Mounts
Both the Sigma 10-20mm F3.5 EX DC HSM and the Canon 20mm f2.8 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 F3.5 EX DC HSM is also available in the Pentax KAF3 , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Sigma 10-20mm F3.5 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 20mm f2.8 USM is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 32mm.
