The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF 28-70mm F2.8 and the Sigma APO 180mm F2.8 EX DG 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. Sigma APO 180mm F2.8 EX DG OS HSM is the longer of the two lenses at 204mm. The Canon RF 28-70mm F2.8 with a length of 92mm, is 112mm shorter. Besides being longer, the Sigma APO 180mm F2.8 EX DG OS HSM also has a larger diameter of 95mm compared to the Canon RF 28-70mm F2.8's 77mm 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 28-70mm F2.8 weighs 494g, which means it is 1146g (69%) lighter than the Sigma APO 180mm F2.8 EX DG OS HSM which has a weight of 1640g.
Filter Threads
The Canon RF 28-70mm F2.8 has a filter size of 67mm whereas the Sigma APO 180mm F2.8 EX DG OS HSM has a 86mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Canon RF 28-70mm F2.8:
And these are the 86mm filters that we recommend for the Sigma APO 180mm F2.8 EX DG OS HSM:
Lens Mounts
The Canon RF 28-70mm F2.8 has the Canon RF lens mount whereas the Sigma APO 180mm F2.8 EX DG OS 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 APO 180mm F2.8 EX DG OS HSM is also available in Nikon F (FX) , Sigma SA and Sony Alpha mounts.
Focal Range
Canon RF 28-70mm F2.8 has a focal range of 28-70mm 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
44.8 - 112mm.
On the other hand, the Sigma APO 180mm F2.8 EX DG OS HSM is a prime lens with fixed focal lenght of 180mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 288mm.