The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 17-70mm F2.8-4 DC OS HSM C and the Canon 15-85mm f3.5-5.6 IS 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 15-85mm f3.5-5.6 IS USM is the longer of the two lenses at 88mm. The Sigma 17-70mm F2.8-4 DC OS HSM C with a length of 82mm, is 6mm shorter. Besides being longer, the Canon 15-85mm f3.5-5.6 IS USM also has a larger diameter of 82mm compared to the Sigma 17-70mm F2.8-4 DC OS HSM C'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 17-70mm F2.8-4 DC OS HSM C weighs 465g, which means it is 110g (19%) lighter than the Canon 15-85mm f3.5-5.6 IS USM which has a weight of 575g.
Filter Threads
Both the Sigma 17-70mm F2.8-4 DC OS HSM C and the Canon 15-85mm f3.5-5.6 IS USM have the same Filter thread size of 72mm.
Below are links to the 72mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Sigma 17-70mm F2.8-4 DC OS HSM C has the Nikon F (DX) lens mount whereas the Canon 15-85mm f3.5-5.6 IS USM has the Canon EF-S lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF-S Mount.
Sigma 17-70mm F2.8-4 DC OS HSM C is also available in the Canon EF , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Sigma 17-70mm F2.8-4 DC OS HSM C has a focal range of 17-70mm and
4.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
25.5-105mm when used on a APS-C / DX format camera.
On the other hand, the Canon 15-85mm f3.5-5.6 IS USM has a focal range of 15-85mm and 5.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 24-136mm when used on a APS-C / DX format camera.
