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 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. Nikon 20mm f1.8G ED is the longer of the two lenses at 81mm. The Sigma 8mm F3.5 EX DG Fisheye with a length of 69mm, is 12mm shorter. Besides being longer, the Nikon 20mm f1.8G ED also has a larger diameter of 83mm 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. Nikon 20mm f1.8G ED weighs 355g, which means it is 45g (11%) lighter than the Sigma 8mm F3.5 EX DG Fisheye which has a weight of 400g.
Lens Mounts
The Nikon 20mm f1.8G ED 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 D6, Nikon D780 and Nikon D3500 for the Nikon F (DX) Mount and Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount.
Sigma 8mm F3.5 EX DG Fisheye is also available in Canon EF and Sigma SA mounts.
Focal Range
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 a 35mm (FF) equivalent of
30mm.
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.
