The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 16mm F1.8 and the Samyang 8mm F2.8 Fisheye for their suitability to various photography scenarios:
Size and Weight Comparison
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 8mm F2.8 Fisheye weighs 265g, 12% (39g) lighter than the Sony FE 16mm F1.8's weight of 304g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Sony E Mount for size comparison purposes.
Ultra-Wideangle Lenses in Sony E Mount for Size Comparison
Lens Mounts
Both the Sony FE 16mm F1.8 and the Samyang 8mm F2.8 Fisheye has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony FX5, Sony A7R VI and Sony A7 V.
Samyang 8mm F2.8 Fisheye is also available in Samsung NX mount.
Focal Range
Sony FE 16mm F1.8 is a prime lens with fixed focal lenght of 16mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
24mm.
On the other hand, the Samyang 8mm F2.8 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.
