The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 10mm f2.8 and the Sigma 8mm F3.5 EX DG 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 10mm f2.8 is the longer of the two lenses at 77mm. The Sigma 8mm F3.5 EX DG Fisheye with a length of 69mm, is 8mm shorter. Besides being longer, the Samyang 10mm f2.8 also has a larger diameter of 86mm compared to the Sigma 8mm F3.5 EX DG Fisheye's 74mm 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. Sigma 8mm F3.5 EX DG Fisheye weighs 400g, 31% (180g) lighter than the Samyang 10mm f2.8's weight of 580g.
Lens Mounts
The Samyang 10mm f2.8 has the Nikon F (DX) lens mount whereas the Sigma 8mm F3.5 EX DG Fisheye has the Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount and Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount.
Samyang 10mm f2.8 is also available in Canon EF , Canon EF-M, Fujifilm X, Four Thirds and Micro Four Thirds mounts.
Sigma 8mm F3.5 EX DG Fisheye is also available in Canon EF and Sigma SA mounts.
Focal Range
Samyang 10mm f2.8 is a prime lens with fixed focal lenght of 10mm which has an effective (full-frame 35mm equivalent) focal range of
15mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 8mm F3.5 EX DG Fisheye is a prime lens with fixed focal lenght of 8mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 12mm.