The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 120-400mm F4.5-5.6 DG OS HSM and the Canon 90-300mm f4.5-5.6 USM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Sigma 120-400mm F4.5-5.6 DG OS HSM is the longer of the two lenses at 203mm. The Canon 90-300mm f4.5-5.6 USM with a length of 115mm, is 88mm shorter. Besides being longer, the Sigma 120-400mm F4.5-5.6 DG OS HSM also has a larger diameter of 92mm compared to the Canon 90-300mm f4.5-5.6 USM's 71mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Canon 90-300mm f4.5-5.6 USM weighs 420g, 74% (1220g) lighter than the Sigma 120-400mm F4.5-5.6 DG OS HSM's weight of 1640g.
Filter Threads
The Sigma 120-400mm F4.5-5.6 DG OS HSM has a filter size of 77mm whereas the Canon 90-300mm f4.5-5.6 USM has a 58mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Sigma 120-400mm F4.5-5.6 DG OS HSM:
And these are the 58mm filters that we recommend for the Canon 90-300mm f4.5-5.6 USM:
Lens Mounts
Both the Sigma 120-400mm F4.5-5.6 DG OS HSM and the Canon 90-300mm f4.5-5.6 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 120-400mm F4.5-5.6 DG OS HSM is also available in Sigma SA and Nikon F (FX) mounts.
Focal Range
Sigma 120-400mm F4.5-5.6 DG OS HSM has a focal range of 120-400mm and
3.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
192 - 640mm.
On the other hand, the Canon 90-300mm f4.5-5.6 USM has a focal range of 90-300mm and 3.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 144 - 480mm.