The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF 100-300mm f2.8 and the Sigma 120-300mm F2.8 EX DG 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 RF 100-300mm f2.8 is the longer of the two lenses at 323mm. The Sigma 120-300mm F2.8 EX DG HSM with a length of 271mm, is 52mm shorter. Besides being longer, the Canon RF 100-300mm f2.8 also has a larger diameter of 128mm compared to the Sigma 120-300mm F2.8 EX DG HSM's 113mm 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 RF 100-300mm f2.8 weighs 2590g, which means it is 10g (0%) lighter than the Sigma 120-300mm F2.8 EX DG HSM which has a weight of 2600g.
Filter Threads
The Canon RF 100-300mm f2.8 has a filter size of 112mm whereas the Sigma 120-300mm F2.8 EX DG HSM has a 105mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 112mm filters that we recommend you to consider for the Canon RF 100-300mm f2.8:
And these are the 105mm filters that we recommend for the Sigma 120-300mm F2.8 EX DG HSM:
Lens Mounts
The Canon RF 100-300mm f2.8 has the Canon RF lens mount whereas the Sigma 120-300mm F2.8 EX DG HSM has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Canon R6 V, Canon R6 III and Canon C50 for the Canon RF Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
Sigma 120-300mm F2.8 EX DG HSM is also available in Sigma SA and Nikon F (FX) mounts.
Focal Range
Canon RF 100-300mm f2.8 has a focal range of 100-300mm and
3.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
160 - 480mm.
On the other hand, the Sigma 120-300mm F2.8 EX DG HSM has a focal range of 120-300mm and 2.5X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 192 - 480mm.
