The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tokina AT-X 14-20mm F2 Pro DX and the Sigma 15mm F2.8 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. Tokina AT-X 14-20mm F2 Pro DX is the longer of the two lenses at 106mm. The Sigma 15mm F2.8 EX DG Fisheye with a length of 65mm, is 41mm shorter. Besides being longer, the Tokina AT-X 14-20mm F2 Pro DX also has a larger diameter of 89mm 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, 48% (355g) lighter than the Tokina AT-X 14-20mm F2 Pro DX's weight of 725g.
Lens Mounts
Both the Tokina AT-X 14-20mm F2 Pro DX and the Sigma 15mm F2.8 EX DG Fisheye has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon T8i, Canon 90D and Canon SL3.
Tokina AT-X 14-20mm F2 Pro DX is also available in Nikon F (DX) mount.
Sigma 15mm F2.8 EX DG Fisheye is also available in Nikon F (FX) , Pentax KAF, Sony Alpha and Sigma SA mounts.
Focal Range
Tokina AT-X 14-20mm F2 Pro DX has a focal range of 14-20mm and
1.4X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
22.4-32mm when used on a APS-C / DX format camera.
On the other hand, the 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 1.6x crop, it provides a 35mm (FF) equivalent of 24mm.