The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Rokinon T-S 24mm f3.5 and the Sigma 20mm F1.4 DG HSM A 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 20mm F1.4 DG HSM A is the longer of the two lenses at 130mm. The Rokinon T-S 24mm f3.5 with a length of 112mm, is 18mm shorter. Besides being longer, the Sigma 20mm F1.4 DG HSM A also has a larger diameter of 91mm compared to the Rokinon T-S 24mm f3.5's 86mm 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. Rokinon T-S 24mm f3.5 weighs 680g, which means it is 270g (28%) lighter than the Sigma 20mm F1.4 DG HSM A which has a weight of 950g.
Lens Mounts
Both the Rokinon T-S 24mm f3.5 and the Sigma 20mm F1.4 DG HSM A has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Rokinon T-S 24mm f3.5 is also available in Nikon F (FX) and Sony Alpha mounts.
Sigma 20mm F1.4 DG HSM A is also available in Nikon F (FX) , Sigma SA and Leica L mounts.
Focal Range
Rokinon T-S 24mm f3.5 is a prime lens with fixed focal lenght of 24mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
38.4mm.
On the other hand, the Sigma 20mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 32mm.