The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 135mm F1.8 DG HSM and the Sony FE 85mm F1.4 GM 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 135mm F1.8 DG HSM is the longer of the two lenses at 141mm. The Sony FE 85mm F1.4 GM with a length of 108mm, is 33mm shorter. Besides being longer, the Sigma 135mm F1.8 DG HSM also has a larger diameter of 91mm compared to the Sony FE 85mm F1.4 GM's 90mm diameter.
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Below you can find a scaled side-by-side image of Sigma 135mm F1.8 DG HSM and Sony FE 85mm F1.4 GM to get a better idea of how their sizes compare in real life.
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. Sony FE 85mm F1.4 GM weighs 820g, 27% (310g) lighter than the Sigma 135mm F1.8 DG HSM's weight of 1130g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Sony E Mount for size comparison purposes.
Telephoto Lenses in Sony E Mount for Size Comparison
Filter Threads
The Sigma 135mm F1.8 DG HSM has a filter size of 82mm whereas the Sony FE 85mm F1.4 GM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 82mm filters that we recommend you to consider for the Sigma 135mm F1.8 DG HSM:
And these are the 77mm filters that we recommend for the Sony FE 85mm F1.4 GM:
Lens Mounts
Both the Sigma 135mm F1.8 DG HSM and the Sony FE 85mm F1.4 GM has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A9 III, Sony A7C Mark II and Sony A7CR.
Sigma 135mm F1.8 DG HSM is also available in Sigma SA , Nikon F (FX) and Canon EF mounts.
Focal Range
Sigma 135mm F1.8 DG HSM is a prime lens with fixed focal lenght of 135mm.
On the other hand, the Sony FE 85mm F1.4 GM 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.