The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 15mm f2.8 Fisheye and the Tamron 18-270mm f3.5-6.3 II VC PZD 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 18-270mm f3.5-6.3 II VC PZD is the longer of the two lenses at 88mm. The Canon 15mm f2.8 Fisheye with a length of 62mm, is 26mm shorter. Besides being longer, the Tamron 18-270mm f3.5-6.3 II VC PZD also has a larger diameter of 74mm 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, which means it is 120g (26%) lighter than the Tamron 18-270mm f3.5-6.3 II VC PZD which has a weight of 450g.
Lens Mounts
Both the Canon 15mm f2.8 Fisheye and the Tamron 18-270mm f3.5-6.3 II VC PZD has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Tamron 18-270mm f3.5-6.3 II VC PZD is also available in Nikon F (DX) mount.
Focal Range
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.
On the other hand, the Tamron 18-270mm f3.5-6.3 II VC PZD has a focal range of 18-270mm and 15.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 28.8-432mm when used on a APS-C / DX format camera.