The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 20mm F2 DG DN C and the Tokina 10-17mm f3.5-4.5 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. Sigma 20mm F2 DG DN C is the longer of the two lenses at 72mm. The Tokina 10-17mm f3.5-4.5 Fisheye with a length of 71mm, is 1mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 70mm.
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. Tokina 10-17mm f3.5-4.5 Fisheye weighs 350g, 5% (20g) lighter than the Sigma 20mm F2 DG DN C's weight of 370g.
Lens Mounts
The Sigma 20mm F2 DG DN C has the Leica L lens mount whereas the Tokina 10-17mm f3.5-4.5 Fisheye has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Leica SL3-P, Panasonic S1 II and Panasonic S1 IIE for the Leica L Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF Mount.
Sigma 20mm F2 DG DN C is also available in the Sony E mount.
Tokina 10-17mm f3.5-4.5 Fisheye is also available in Nikon F (DX) mount.
Focal Range
Sigma 20mm F2 DG DN C 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 Tokina 10-17mm f3.5-4.5 Fisheye has a focal range of 10-17mm and 1.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 16-27.2mm when used on a APS-C / DX format camera.
