The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang AF 14mm F2.8 and the Samyang 12mm f2.0 for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Samyang AF 14mm F2.8 is the longer of the two lenses at 98mm. The Samyang 12mm f2.0 with a length of 59mm is 39mm shorter. Besides being longer, the Samyang AF 14mm F2.8 also has a larger diameter of 86mm compared to Samyang 12mm f2.0's 73mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Samyang 12mm f2.0 weighs 260g, 48% (245g) lighter than the Samyang AF 14mm F2.8's weight of 505g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Sony E Mount for size comparison purposes.
Wideangle Prime Lenses in Sony E Mount for Size Comparison
Both Samyang AF 14mm F2.8 and Samyang 12mm f2.0 has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A7R V, Sony FX30 and Sony A7 IV.
Samyang 12mm f2.0 is also available in Canon EF-M , Fujifilm X, Micro Four Thirds and Samsung NX mounts.
Samyang AF 14mm F2.8 is a prime lens with fixed focal lenght of 14mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 21mm.
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.