The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 20mm F1.8 and the Samsung D-Xenon 12-24mm F4 ED for their suitability to various photography scenarios:
Size and Weight Comparison
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. Samsung D-Xenon 12-24mm F4 ED weighs 430g, 13% (67g) lighter than the Samyang 20mm F1.8's weight of 497g.
Filter Threads
Both the Samyang 20mm F1.8 and the Samsung D-Xenon 12-24mm F4 ED have the same Filter thread size of 77mm.
Below are links to the 77mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Samyang 20mm F1.8 has the Pentax KAF lens mount whereas the Samsung D-Xenon 12-24mm F4 ED has the Pentax KAF2 lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount and , and for the Pentax KAF2 Mount.
Samyang 20mm F1.8 is also available in the Canon EF , Canon EF-M, Fujifilm X, Micro Four Thirds, Nikon F (FX), Samsung NX, Sony Alpha and Sony E mounts.
Focal Range
Samyang 20mm F1.8 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 Samsung D-Xenon 12-24mm F4 ED has a focal range of 12-24mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 18-36mm when used on a APS-C / DX format camera.
