The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Rokinon 8mm f3.5 Fisheye and the Canon 20-35mm f3.5-4.5 USM 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 8mm f3.5 Fisheye is the longer of the two lenses at 77mm. The Canon 20-35mm f3.5-4.5 USM with a length of 69mm, is 8mm shorter. On the other hand, the Canon 20-35mm f3.5-4.5 USM has a larger diameter of 84mm compared to the Rokinon 8mm f3.5 Fisheye's 75mm 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. Canon 20-35mm f3.5-4.5 USM weighs 340g, 23% (103g) lighter than the Rokinon 8mm f3.5 Fisheye's weight of 443g.
Lens Mounts
Both the Rokinon 8mm f3.5 Fisheye and the Canon 20-35mm f3.5-4.5 USM 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.
Rokinon 8mm f3.5 Fisheye is also available in the Nikon F (FX) , Four Thirds, Pentax KAF, Sony Alpha and Samsung NX mounts.
Focal Range
Rokinon 8mm f3.5 Fisheye is a prime lens with fixed focal lenght of 8mm which has an effective (full-frame 35mm equivalent) focal range of
12.8mm when used on a APS-C / DX format camera.
On the other hand, the Canon 20-35mm f3.5-4.5 USM has a focal range of 20-35mm and 1.8X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 32 - 56mm.
