The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon EF 70-200 F2.8L IS III USM and the Sigma 18-125mm F3.8-5.6 DC OS HSM 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 EF 70-200 F2.8L IS III USM is the longer of the two lenses at 199mm. The Sigma 18-125mm F3.8-5.6 DC OS HSM with a length of 89mm, is 110mm shorter. Besides being longer, the Canon EF 70-200 F2.8L IS III USM also has a larger diameter of 89mm compared to the Sigma 18-125mm F3.8-5.6 DC OS HSM's 74mm 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 18-125mm F3.8-5.6 DC OS HSM weighs 490g, 65% (950g) lighter than the Canon EF 70-200 F2.8L IS III USM's weight of 1440g.
Filter Threads
The Canon EF 70-200 F2.8L IS III USM has a filter size of 77mm whereas the Sigma 18-125mm F3.8-5.6 DC OS HSM has a 67mm 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 Canon EF 70-200 F2.8L IS III USM:
And these are the 67mm filters that we recommend for the Sigma 18-125mm F3.8-5.6 DC OS HSM:
Lens Mounts
The Canon EF 70-200 F2.8L IS III USM has the Canon EF lens mount whereas the Sigma 18-125mm F3.8-5.6 DC OS HSM has the Sigma SA lens mount. Some of the latest released cameras that are compatible with these mounts are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount and Sigma SD1 Merrill, Sigma SD1 and for the Sigma SA Mount.
Sigma 18-125mm F3.8-5.6 DC OS HSM is also available in Canon EF and Nikon F (DX) mounts.
Focal Range
Canon EF 70-200 F2.8L IS III USM 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 a 35mm (FF) equivalent of
112 - 320mm.
On the other hand, the Sigma 18-125mm F3.8-5.6 DC OS HSM has a focal range of 18-125mm and 6.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-187.5mm when used on a APS-C / DX format camera.
