The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 16-35mm F2.8L III and the Sigma 18-35mm F1.8 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. Canon 16-35mm F2.8L III is the longer of the two lenses at 128mm. The Sigma 18-35mm F1.8 DC HSM with a length of 121mm, is 7mm shorter. Besides being longer, the Canon 16-35mm F2.8L III also has a larger diameter of 89mm compared to the Sigma 18-35mm F1.8 DC HSM's 78mm diameter.
ss
Below you can find a scaled side-by-side image of Canon 16-35mm F2.8L III and Sigma 18-35mm F1.8 DC HSM to get a better idea of how their sizes compare in real life.
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 16-35mm F2.8L III weighs 790g, which means it is 20g (2%) lighter than the Sigma 18-35mm F1.8 DC HSM which has a weight of 810g.
Filter Threads
The Canon 16-35mm F2.8L III has a filter size of 82mm whereas the Sigma 18-35mm F1.8 DC HSM 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 Canon 16-35mm F2.8L III:
And these are the 72mm filters that we recommend for the Sigma 18-35mm F1.8 DC HSM:
Lens Mounts
Both the Canon 16-35mm F2.8L III and the Sigma 18-35mm F1.8 DC HSM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Sigma 18-35mm F1.8 DC HSM is also available in Pentax KAF , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Canon 16-35mm F2.8L III has a focal range of 16-35mm and
2.2X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
25.6 - 56mm.
On the other hand, the Sigma 18-35mm F1.8 DC HSM has a focal range of 18-35mm and 1.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 28.8-56mm when used on a APS-C / DX format camera.