The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 120-300mm F2.8 EX DG OS HSM and the Canon 85mm f1.8 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 120-300mm F2.8 EX DG OS HSM is the longer of the two lenses at 289mm. The Canon 85mm f1.8 USM with a length of 72mm, is 217mm shorter. Besides being longer, the Sigma 120-300mm F2.8 EX DG OS HSM also has a larger diameter of 114mm compared to the Canon 85mm f1.8 USM's 75mm 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 85mm f1.8 USM weighs 425g, 85% (2525g) lighter than the Sigma 120-300mm F2.8 EX DG OS HSM's weight of 2950g.
Filter Threads
The Sigma 120-300mm F2.8 EX DG OS HSM has a filter size of 105mm whereas the Canon 85mm f1.8 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 105mm filters that we recommend you to consider for the Sigma 120-300mm F2.8 EX DG OS HSM:
And these are the 58mm filters that we recommend for the Canon 85mm f1.8 USM:
Lens Mounts
Both the Sigma 120-300mm F2.8 EX DG OS HSM and the Canon 85mm f1.8 USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K.
Sigma 120-300mm F2.8 EX DG OS HSM is also available in the Nikon F (FX) mount.
Focal Range
Sigma 120-300mm F2.8 EX DG OS 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.
On the other hand, the Canon 85mm f1.8 USM is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 136mm.
