The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 17-50mm f2.8 XR II LD and the Canon 17-55mm f2.8 IS USM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Canon 17-55mm f2.8 IS USM is the longer of the two lenses at 111mm. The Tamron 17-50mm f2.8 XR II LD with a length of 82mm is 29mm shorter. Besides being longer, the Canon 17-55mm f2.8 IS USM also has a larger diameter of 84mm compared to Tamron 17-50mm f2.8 XR II LD's 74mm diameter.
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. Tamron 17-50mm f2.8 XR II LD weighs 430g, which means it is 215g (33%) lighter than the Canon 17-55mm f2.8 IS USM which has a weight of 645g.
Lens Mounts
Both Tamron 17-50mm f2.8 XR II LD has the Canon EF lens mount whereas the Canon 17-55mm f2.8 IS USM has the Canon EF-S lens mount. Some of the latest released cameras that are compatible with these mounts are Canon T8i, Canon 90D and Canon SL3 for the Canon EF Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF-S Mount.
Tamron 17-50mm f2.8 XR II LD is also available in Nikon F (DX) , Sony Alpha and Pentax KAF mounts.
Focal Range
Tamron 17-50mm f2.8 XR II LD has a focal range of 17-50mm and 2.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27.2-80mm when used on a APS-C / DX format camera. Canon 17-55mm f2.8 IS USM has a focal range of 17-55mm and 3.2X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27.2-88mm when used on a APS-C / DX format camera.