The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 8mm F3.5 EX DG Fisheye and the Nikon 20mm f2.8D 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. Sigma 8mm F3.5 EX DG Fisheye is the longer of the two lenses at 69mm. The Nikon 20mm f2.8D with a length of 43mm, is 26mm shorter. Besides being longer, the Sigma 8mm F3.5 EX DG Fisheye also has a larger diameter of 74mm compared to the Nikon 20mm f2.8D's 69mm 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 f2.8D weighs 270g, 32% (130g) lighter than the Sigma 8mm F3.5 EX DG Fisheye's weight of 400g.
Below you can find the dimension and weight table of the Wideangle Fisheye Prime Lenses in Nikon F (FX) Mount for size comparison purposes.
Ultra-Wideangle Lenses in Nikon F (FX) Mount for Size Comparison
Lens Mounts
Both the Sigma 8mm F3.5 EX DG Fisheye and the Nikon 20mm f2.8D has the same Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (FX) lenses are Nikon D6, Nikon D780 and Nikon D3500.
Sigma 8mm F3.5 EX DG Fisheye is also available in the Canon EF and Sigma SA mounts.
Focal Range
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.
On the other hand, the Nikon 20mm f2.8D 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.
