The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 15mm F2.8 EX DG Fisheye and the Rokinon 14mm f2.8 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. Rokinon 14mm f2.8 is the longer of the two lenses at 96mm. The Sigma 15mm F2.8 EX DG Fisheye with a length of 65mm, is 31mm shorter. Besides being longer, the Rokinon 14mm f2.8 also has a larger diameter of 87mm compared to the Sigma 15mm F2.8 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 15mm F2.8 EX DG Fisheye weighs 370g, which means it is 182g (32%) lighter than the Rokinon 14mm f2.8 which has a weight of 552g.
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 15mm F2.8 EX DG Fisheye and the Rokinon 14mm f2.8 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 15mm F2.8 EX DG Fisheye is also available in Canon EF , Pentax KAF, Sony Alpha and Sigma SA mounts.
Rokinon 14mm f2.8 is also available in Canon EF , Four Thirds, Pentax KAF, Sony Alpha and Samsung NX mounts.
Focal Range
Sigma 15mm F2.8 EX DG Fisheye is a prime lens with fixed focal lenght of 15mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
22.5mm.
On the other hand, the Rokinon 14mm f2.8 is a prime lens with fixed focal lenght of 14mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 21mm.