The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 105mm F1.4 DG HSM and the Sony FE 85mm F1.4 GM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 105mm F1.4 DG HSM is the longer of the two lenses at 132mm. The Sony FE 85mm F1.4 GM with a length of 108mm is 24mm shorter. Besides being longer, the Sigma 105mm F1.4 DG HSM also has a larger diameter of 116mm compared to Sony FE 85mm F1.4 GM's 90mm diameter.
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. Sony FE 85mm F1.4 GM weighs 820g, 50% (825g) lighter than the Sigma 105mm F1.4 DG HSM's weight of 1645g.
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 Sigma 105mm F1.4 DG HSM and 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 FX30, Sony ZV-E10 and Sony A6600.
Sigma 105mm F1.4 DG HSM is also available in Canon EF , Nikon F (FX) and Sigma SA mounts.
Focal Range
Sigma 105mm F1.4 DG HSM is a prime lens with fixed focal lenght of 105mm which has an effective (full-frame 35mm equivalent) focal range of 157.5mm when used on a 35mm FF format camera. 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 an 35mm (FF) equivalent of 127.5mm.