The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 70-200 F2.8 DG OS HSM S and the Canon 75-300mm f4.0-5.6 III 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 70-200 F2.8 DG OS HSM S is the longer of the two lenses at 203mm. The Canon 75-300mm f4.0-5.6 III with a length of 122mm is 81mm shorter. Besides being longer, the Sigma 70-200 F2.8 DG OS HSM S also has a larger diameter of 94mm compared to Canon 75-300mm f4.0-5.6 III's 71mm 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.
Below you can find the dimension and weight table of the 'Telephoto Zoom Lenses in Canon EF Mount for size comparison purposes.
Telephoto Zoom Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both Sigma 70-200 F2.8 DG OS HSM S and Canon 75-300mm f4.0-5.6 III 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 70-200 F2.8 DG OS HSM S is also available in Nikon F (FX) and Sigma SA mounts.
Focal Range
Sigma 70-200 F2.8 DG OS HSM S has a focal range of 70-200mm 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 112 - 320mm.
Canon 75-300mm f4.0-5.6 III has a focal range of 75-300mm and 4.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 120 - 480mm.