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 28-80mm f3.5-5.6 II for their suitability to various photography scenarios:
Size and Weight Comparison
The 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 28-80mm f3.5-5.6 II with a length of 71mm, is 50mm shorter. Besides being longer, the Sigma 18-35mm F1.8 DC HSM also has a larger diameter of 78mm compared to the Canon 28-80mm f3.5-5.6 II's 67mm diameter.
The 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 28-80mm f3.5-5.6 II weighs 220g, 72% (590g) 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 the Sigma 18-35mm F1.8 DC HSM and the Canon 28-80mm f3.5-5.6 II 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 28-80mm f3.5-5.6 II has a focal range of 28-80mm and 2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 44.8 - 128mm.