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 DG OS HSM and the Nikon 85mm f1.8G 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 DG OS HSM is the longer of the two lenses at 291mm. The Nikon 85mm f1.8G with a length of 73mm, is 218mm shorter. Besides being longer, the Sigma 120-300mm F2.8 DG OS HSM also has a larger diameter of 124mm compared to the Nikon 85mm f1.8G's 80mm 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. Nikon 85mm f1.8G weighs 350g, 88% (2600g) lighter than the Sigma 120-300mm F2.8 DG OS HSM's weight of 2950g.
Filter Threads
The Sigma 120-300mm F2.8 DG OS HSM has a filter size of 105mm whereas the Nikon 85mm f1.8G 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 105mm filters that we recommend you to consider for the Sigma 120-300mm F2.8 DG OS HSM:
And these are the 67mm filters that we recommend for the Nikon 85mm f1.8G:
Lens Mounts
Both the Sigma 120-300mm F2.8 DG OS HSM and the Nikon 85mm f1.8G has the same Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (FX) lenses are Nikon D6, Nikon D780 and Nikon D3500.
Sigma 120-300mm F2.8 DG OS HSM is also available in the Canon EF and Sigma SA mounts.
Focal Range
Sigma 120-300mm F2.8 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 1.5x crop, it provides a 35mm (FF) equivalent of
180 - 450mm.
On the other hand, the Nikon 85mm f1.8G is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 127.5mm.
