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 Samyang AF 85mm F1.4 FE for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Sigma 135mm F1.8 DG HSM is the longer of the two lenses at 141mm. The Samyang AF 85mm F1.4 FE with a length of 100mm, is 41mm shorter. Besides being longer, the Sigma 135mm F1.8 DG HSM also has a larger diameter of 91mm compared to the Samyang AF 85mm F1.4 FE's 88mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Samyang AF 85mm F1.4 FE weighs 568g, 49% (562g) 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 Prime Lenses in Sony E Mount for Size Comparison
Lens Mounts
Both the Sigma 135mm F1.8 DG HSM and the Samyang AF 85mm F1.4 FE has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony ZV-E1, Sony A7R V and Sony FX30.
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. Samyang AF 85mm F1.4 FE 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.