The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 15-30mm f2.8 VC USD 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 an important deciding factor when comparing two lenses. Tamron 15-30mm f2.8 VC USD is the longer of the two lenses at 145mm. The Canon 20-35mm f3.5-4.5 USM with a length of 69mm, is 76mm shorter. Besides being longer, the Tamron 15-30mm f2.8 VC USD also has a larger diameter of 98mm compared to the Canon 20-35mm f3.5-4.5 USM's 84mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Canon 20-35mm f3.5-4.5 USM weighs 340g, 69% (760g) lighter than the Tamron 15-30mm f2.8 VC USD's weight of 1100g.
Below you can find the dimension and weight table of the Wideangle Zoom Lenses in Canon EF Mount for size comparison purposes.
Wideangle Zoom Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both the Tamron 15-30mm f2.8 VC USD 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 1D X III, Canon 6D MII and Canon 5D MIV.
Tamron 15-30mm f2.8 VC USD is also available in Nikon F (FX) and Sony Alpha mounts.
Focal Range
Tamron 15-30mm f2.8 VC USD has a focal range of 15-30mm and 2.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 24 - 48mm.
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.