The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Nikon 20mm f1.8G ED and the Samyang 16mm 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 16mm f2.0 is the longer of the two lenses at 89mm. The Nikon 20mm f1.8G ED with a length of 81mm is 8mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 83mm.
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. Nikon 20mm f1.8G ED weighs 355g, which means it is 228g (39%) lighter than the Samyang 16mm f2.0 which has a weight of 583g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Nikon F (DX) Mount for size comparison purposes.
Wideangle Prime Lenses in Nikon F (DX) Mount for Size Comparison
Both Nikon 20mm f1.8G ED and Samyang 16mm f2.0 has the same Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (DX) lenses are Nikon D6, Nikon D780 and Nikon D3500.
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.
Nikon 20mm f1.8G ED 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 an 35mm (FF) equivalent of 30mm.
Samyang 16mm f2.0 is a prime lens with fixed focal lenght of 16mm which has a 35mm equivalent focal range of 30mm when used on a APS-C / DX format camera.