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 Sigma 12-24mm F4.5-5.6 EX DG HSM 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 12-24mm F4.5-5.6 EX DG HSM is the longer of the two lenses at 103mm. The Sigma 20mm F1.8 EX DG RF with a length of 90mm, is 13mm shorter. On the other hand, the Sigma 20mm F1.8 EX DG RF has a larger diameter of 89mm compared to the Sigma 12-24mm F4.5-5.6 EX DG HSM's 87mm 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 80g (13%) lighter than the Sigma 12-24mm F4.5-5.6 EX DG HSM which has a weight of 600g.
Lens Mounts
Both the Sigma 20mm F1.8 EX DG RF and the Sigma 12-24mm F4.5-5.6 EX DG HSM has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Sigma 20mm F1.8 EX DG RF is also available in the Canon EF , Nikon F (DX), Sony Alpha and Sigma SA mounts.
Sigma 12-24mm F4.5-5.6 EX DG HSM is also available in Canon EF , Sony Alpha, Sigma SA 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 Sigma 12-24mm F4.5-5.6 EX DG HSM has a focal range of 12-24mm and 2.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 18 - 36mm.
