The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 20mm f2.8 USM and the Canon 8-15mm f4L Fisheye 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. Canon 8-15mm f4L Fisheye USM is the longer of the two lenses at 83mm. The Canon 20mm f2.8 USM with a length of 71mm, is 12mm shorter. Besides being longer, the Canon 8-15mm f4L Fisheye USM also has a larger diameter of 79mm compared to the Canon 20mm f2.8 USM's 78mm 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 20mm f2.8 USM weighs 405g, which means it is 135g (25%) lighter than the Canon 8-15mm f4L Fisheye USM which has a weight of 540g.
Lens Mounts
Both the Canon 20mm f2.8 USM and the Canon 8-15mm f4L Fisheye USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K.
Focal Range
Canon 20mm f2.8 USM is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
32mm.
On the other hand, the Canon 8-15mm f4L Fisheye USM has a focal range of 8-15mm and 1.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 12.8 - 24mm.
