The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Rokinon 85mm F1.8 and the Sigma 105mm F1.4 DG HSM 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 Rokinon 85mm F1.8 with a length of 81mm is 51mm shorter. Besides being longer, the Sigma 105mm F1.4 DG HSM also has a larger diameter of 116mm compared to Rokinon 85mm F1.8's 68mm 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. Rokinon 85mm F1.8 weighs 344g, which means it is 1301g (79%) lighter than the Sigma 105mm F1.4 DG HSM which has a 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
Both Rokinon 85mm F1.8 and Sigma 105mm F1.4 DG HSM 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.
Rokinon 85mm F1.8 is also available in Canon EF-M and Fujifilm X mounts.
Sigma 105mm F1.4 DG HSM is also available in Canon EF , Nikon F (FX) and Sigma SA mounts.
Rokinon 85mm F1.8 is a prime lens with fixed focal lenght of 85mm which has an effective (full-frame 35mm equivalent) focal range of 127.5mm when used on a APS-C / DX format camera. 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.