The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 10-18mm f4.5-5.6 IS STM and the Sigma 10-20mm F4-5.6 EX DC HSM 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 F4-5.6 EX DC HSM is the longer of the two lenses at 81mm. The Canon 10-18mm f4.5-5.6 IS STM with a length of 72mm, is 9mm shorter. Besides being longer, the Sigma 10-20mm F4-5.6 EX DC HSM also has a larger diameter of 84mm compared to the Canon 10-18mm f4.5-5.6 IS STM's 75mm 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 10-18mm f4.5-5.6 IS STM weighs 240g, which means it is 230g (48%) lighter than the Sigma 10-20mm F4-5.6 EX DC HSM which has a weight of 470g.
Filter Threads
The Canon 10-18mm f4.5-5.6 IS STM has a filter size of 67mm whereas the Sigma 10-20mm F4-5.6 EX DC HSM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Canon 10-18mm f4.5-5.6 IS STM:
And these are the 77mm filters that we recommend for the Sigma 10-20mm F4-5.6 EX DC HSM:
Lens Mounts
The Canon 10-18mm f4.5-5.6 IS STM has the Canon EF-S lens mount whereas the Sigma 10-20mm F4-5.6 EX DC HSM has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Canon T8i, Canon 90D and Canon SL3 for the Canon EF-S Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF Mount.
Sigma 10-20mm F4-5.6 EX DC HSM is also available in Four Thirds , Pentax KAF, Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Canon 10-18mm f4.5-5.6 IS STM has a focal range of 10-18mm and
1.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
16-28.8mm when used on a APS-C / DX format camera.
On the other hand, the 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.