The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 20mm F1.8 EX DG RF and the Rokinon T-S 24mm f3.5 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. Rokinon T-S 24mm f3.5 is the longer of the two lenses at 112mm. The Sigma 20mm F1.8 EX DG RF with a length of 90mm, is 22mm shorter. On the other hand, the Sigma 20mm F1.8 EX DG RF has a larger diameter of 89mm 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. Sigma 20mm F1.8 EX DG RF weighs 520g, which means it is 160g (23%) lighter than the Rokinon T-S 24mm f3.5 which has a weight of 680g.
Filter Threads
Both the Sigma 20mm F1.8 EX DG RF and the Rokinon T-S 24mm f3.5 have the same Filter thread size of 82mm.
Below are links to the 82mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Sigma 20mm F1.8 EX DG RF and the Rokinon T-S 24mm f3.5 has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Sigma 20mm F1.8 EX DG RF is also available in Canon EF , Nikon F (DX), Pentax KAF and Sigma SA mounts.
Rokinon T-S 24mm f3.5 is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Sigma 20mm F1.8 EX DG RF is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
30mm.
On the other hand, the 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 1.5x crop, it provides a 35mm (FF) equivalent of 36mm.