The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon EF 600mm F4L IS III USM and the Sigma 85mm F1.4 EX DG HSM 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. Canon EF 600mm F4L IS III USM is the longer of the two lenses at 448mm. The Sigma 85mm F1.4 EX DG HSM with a length of 88mm, is 360mm shorter. Besides being longer, the Canon EF 600mm F4L IS III USM also has a larger diameter of 168mm compared to the Sigma 85mm F1.4 EX DG HSM's 86mm 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. Sigma 85mm F1.4 EX DG HSM weighs 725g, 76% (2325g) lighter than the Canon EF 600mm F4L IS III USM's weight of 3050g.
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 Canon EF 600mm F4L IS III USM and the Sigma 85mm F1.4 EX DG 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 85mm F1.4 EX DG HSM is also available in Nikon F (FX) , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Canon EF 600mm F4L IS III USM is a prime lens with fixed focal lenght of 600mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 960mm.
Sigma 85mm F1.4 EX DG HSM is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 136mm.