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 800mm F5.6 EX DG HSM 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 800mm F5.6 EX DG HSM is the longer of the two lenses at 521mm. The Canon EF 600mm F4L IS III USM with a length of 448mm is 73mm shorter. On the other hand, the Canon EF 600mm F4L IS III USM has a larger diameter of 168mm compared to Sigma 800mm F5.6 EX DG HSM's 157mm 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 EF 600mm F4L IS III USM weighs 3050g, which means it is 1850g (37%) lighter than the Sigma 800mm F5.6 EX DG HSM which has a weight of 4900g.
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 Canon EF 600mm F4L IS III USM and Sigma 800mm F5.6 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 800mm F5.6 EX DG HSM is also available in Nikon F (FX) 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 an 35mm (FF) equivalent of 960mm.
Sigma 800mm F5.6 EX DG HSM is a prime lens with fixed focal lenght of 800mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 1280mm.