The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-35mm F1.8 DC HSM and the Canon 24-70mm f4L IS USM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 18-35mm F1.8 DC HSM is the longer of the two lenses at 121mm. The Canon 24-70mm f4L IS USM with a length of 93mm is 28mm shorter. On the other hand, the Canon 24-70mm f4L IS USM has a larger diameter of 83mm compared to Sigma 18-35mm F1.8 DC HSM's 78mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Canon 24-70mm f4L IS USM weighs 600g, 25% (210g) lighter than the Sigma 18-35mm F1.8 DC HSM's weight of 810g.
Below you can find the dimension and weight table of the 'Standard Zoom Lenses in Canon EF Mount for size comparison purposes.
Standard Zoom Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both Sigma 18-35mm F1.8 DC HSM and Canon 24-70mm f4L IS 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 18-35mm F1.8 DC HSM is also available in Pentax KAF , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
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. Canon 24-70mm f4L IS USM has a focal range of 24-70mm and 2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 38.4 - 112mm.