The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 85mm F1.4 EX DG HSM and the Canon 85mm f1.8 USM 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 85mm F1.4 EX DG HSM is the longer of the two lenses at 88mm. The Canon 85mm f1.8 USM with a length of 72mm, is 16mm shorter. Besides being longer, the Sigma 85mm F1.4 EX DG HSM also has a larger diameter of 86mm compared to the Canon 85mm f1.8 USM's 75mm 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 85mm f1.8 USM weighs 425g, 41% (300g) lighter than the Sigma 85mm F1.4 EX DG HSM's weight of 725g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Canon EF Mount for size comparison purposes.
Telephoto Prime Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both the Sigma 85mm F1.4 EX DG HSM and the Canon 85mm f1.8 USM 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 85mm F1.4 EX DG HSM is also available in Nikon F (FX) , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Both lenses have the same focal range of 85mm but while Sigma 85mm F1.4 EX DG HSM has the fastest aperture of F1.4, the Canon 85mm f1.8 USM's widest aperture value is F1.8.