The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-300 F3.5-6.3 DC OS HSM and the Canon 100-400mm f4.5-5.6L IS 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. Canon 100-400mm f4.5-5.6L IS USM is the longer of the two lenses at 189mm. The Sigma 18-300 F3.5-6.3 DC OS HSM with a length of 102mm, is 87mm shorter. Besides being longer, the Canon 100-400mm f4.5-5.6L IS USM also has a larger diameter of 92mm compared to the Sigma 18-300 F3.5-6.3 DC OS HSM's 79mm 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. Sigma 18-300 F3.5-6.3 DC OS HSM weighs 585g, which means it is 795g (57%) lighter than the Canon 100-400mm f4.5-5.6L IS USM which has a weight of 1380g.
Below you can find the dimension and weight table of the SuperZoom Lenses in Canon EF Mount for size comparison purposes.
Super Telephoto Lenses in Canon EF Mount for Size Comparison
Filter Threads
The Sigma 18-300 F3.5-6.3 DC OS HSM has a filter size of 72mm whereas the Canon 100-400mm f4.5-5.6L IS USM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 72mm filters that we recommend you to consider for the Sigma 18-300 F3.5-6.3 DC OS HSM:
And these are the 77mm filters that we recommend for the Canon 100-400mm f4.5-5.6L IS USM:
Lens Mounts
Both the Sigma 18-300 F3.5-6.3 DC OS HSM and the Canon 100-400mm f4.5-5.6L IS USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon T8i, Canon 90D and Canon SL3.
Sigma 18-300 F3.5-6.3 DC OS HSM is also available in the Nikon F (DX) , Pentax KAF3, Sigma SA and Sony Alpha mounts.
Focal Range
Sigma 18-300 F3.5-6.3 DC OS HSM has a focal range of 18-300mm and
16.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-480mm when used on a APS-C / DX format camera.
On the other hand, the Canon 100-400mm f4.5-5.6L IS USM has a focal range of 100-400mm and 4.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 160 - 640mm.
