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 Rokinon 8mm f3.5 Fisheye 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. Samyang 20mm F1.8 is the longer of the two lenses at 88mm. The Rokinon 8mm f3.5 Fisheye with a length of 77mm, is 11mm shorter. Besides being longer, the Samyang 20mm F1.8 also has a larger diameter of 83mm compared to the Rokinon 8mm f3.5 Fisheye's 75mm 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. Rokinon 8mm f3.5 Fisheye weighs 443g, 10% (54g) lighter than the Samyang 20mm F1.8's weight of 497g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Samsung NX Mount for size comparison purposes.
Ultra-Wideangle Lenses in Samsung NX Mount for Size Comparison
Lens Mounts
Both the Samyang 20mm F1.8 and the Rokinon 8mm f3.5 Fisheye has the same Samsung NX lens mount. Some of the latest released cameras that are compatible with the Samsung NX lenses are Samsung NX500, Samsung NX1 and Samsung NX3000.
Samyang 20mm F1.8 is also available in the Canon EF , Canon EF-M, Fujifilm X, Micro Four Thirds, Nikon F (FX), Pentax KAF, Sony Alpha and Sony E mounts.
Rokinon 8mm f3.5 Fisheye is also available in Canon EF , Nikon F (FX), Four Thirds, Pentax KAF and Sony Alpha mounts.
Focal Range
Samyang 20mm F1.8 is a prime lens with fixed focal lenght of 20mm.
On the other hand, the Rokinon 8mm f3.5 Fisheye is a prime lens with fixed focal lenght of 8mm which has an effective (full-frame 35mm equivalent) focal range of 12mm when used on a APS-C / DX format camera.
