The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 14mm F1.8 DG HSM and the Samyang 16mm f2.0 for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Sigma 14mm F1.8 DG HSM is the longer of the two lenses at 126mm. The Samyang 16mm f2.0 with a length of 89mm, is 37mm shorter. Besides being longer, the Sigma 14mm F1.8 DG HSM also has a larger diameter of 95mm compared to the Samyang 16mm f2.0's 83mm diameter.
The 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 16mm f2.0 weighs 583g, 50% (587g) lighter than the Sigma 14mm F1.8 DG HSM's weight of 1170g.
Lens Mounts
The Sigma 14mm F1.8 DG HSM has the Nikon F (FX) lens mount whereas the Samyang 16mm f2.0 has the Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount and Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount.
Sigma 14mm F1.8 DG HSM is also available in Sigma SA and Canon EF mounts.
Samyang 16mm f2.0 is also available in Canon EF , Canon EF-M, Fujifilm X, Four Thirds, Micro Four Thirds, Pentax KAF, Sony Alpha, Sony E and Samsung NX mounts.
Focal Range
Sigma 14mm F1.8 DG HSM 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 a 35mm (FF) equivalent of 21mm.
Samyang 16mm f2.0 is a prime lens with fixed focal lenght of 16mm which has an effective (full-frame 35mm equivalent) focal range of 24mm when used on a APS-C / DX format camera.