The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 17-35mm f2.8-4 LD and the Canon 15mm f2.8 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. Tamron 17-35mm f2.8-4 LD is the longer of the two lenses at 87mm. The Canon 15mm f2.8 Fisheye with a length of 62mm, is 25mm shorter. Besides being longer, the Tamron 17-35mm f2.8-4 LD also has a larger diameter of 83mm compared to the Canon 15mm f2.8 Fisheye's 73mm 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 15mm f2.8 Fisheye weighs 330g, 25% (110g) lighter than the Tamron 17-35mm f2.8-4 LD's weight of 440g.
Lens Mounts
Both the Tamron 17-35mm f2.8-4 LD and the Canon 15mm f2.8 Fisheye 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.
Tamron 17-35mm f2.8-4 LD is also available in the Nikon F (FX) mount.
Focal Range
Tamron 17-35mm f2.8-4 LD has a focal range of 17-35mm and
2.1X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
27.2 - 56mm.
On the other hand, the Canon 15mm f2.8 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.