The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 12mm f2.0 and the Rokinon 14mm f2.8 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 14mm f2.8 is the longer of the two lenses at 96mm. The Samyang 12mm f2.0 with a length of 59mm, is 37mm shorter. Besides being longer, the Rokinon 14mm f2.8 also has a larger diameter of 87mm compared to the Samyang 12mm f2.0's 73mm 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. Samyang 12mm f2.0 weighs 260g, which means it is 292g (52%) lighter than the Rokinon 14mm f2.8 which has a weight of 552g.
Lens Mounts
The Samyang 12mm f2.0 has the Fujifilm X lens mount whereas the Rokinon 14mm f2.8 has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Fujifilm X-S20, Fujifilm X-T5 and Fujifilm X-H2 for the Fujifilm X Mount and Canon 1D X III, Canon 6D MII and Canon 5D MIV for the Canon EF Mount.
Samyang 12mm f2.0 is also available in Canon EF-M , Micro Four Thirds, Sony E and Samsung NX mounts.
Rokinon 14mm f2.8 is also available in Nikon F (FX) , Four Thirds, Pentax KAF, Sony Alpha and Samsung NX mounts.
Focal Range
Samyang 12mm f2.0 is a prime lens with fixed focal lenght of 12mm which has an effective (full-frame 35mm equivalent) focal range of
18mm when used on a APS-C / DX format camera.
On the other hand, the Rokinon 14mm f2.8 is a prime lens with fixed focal lenght of 14mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 22.4mm.