The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 20mm F1.4 DG HSM A and the Nikon Fisheye-16mm 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 20mm F1.4 DG HSM A is the longer of the two lenses at 130mm. The Nikon Fisheye-16mm f2.8D with a length of 57mm, is 73mm shorter. Besides being longer, the Sigma 20mm F1.4 DG HSM A also has a larger diameter of 91mm compared to the Nikon Fisheye-16mm f2.8D's 63mm 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 Fisheye-16mm f2.8D weighs 290g, 69% (660g) lighter than the Sigma 20mm F1.4 DG HSM A's weight of 950g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Nikon F (FX) Mount for size comparison purposes.
Ultra-Wideangle Lenses in Nikon F (FX) Mount for Size Comparison
Both the Sigma 20mm F1.4 DG HSM A and the Nikon Fisheye-16mm 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 20mm F1.4 DG HSM A is also available in Canon EF , Sigma SA and Leica L mounts.
Sigma 20mm F1.4 DG HSM A 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 Nikon Fisheye-16mm f2.8D 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.