The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 18-135mm F3.5-5.6 IS and the Tamron 17-50mm f2.8 XR II LD 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 18-135mm F3.5-5.6 IS is the longer of the two lenses at 96mm. The Tamron 17-50mm f2.8 XR II LD with a length of 82mm, is 14mm shorter. Besides being longer, the Canon 18-135mm F3.5-5.6 IS also has a larger diameter of 77mm compared to the Tamron 17-50mm f2.8 XR II LD's 74mm 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. Tamron 17-50mm f2.8 XR II LD weighs 430g, 16% (85g) lighter than the Canon 18-135mm F3.5-5.6 IS's weight of 515g.
Filter Threads
Both the Canon 18-135mm F3.5-5.6 IS and the Tamron 17-50mm f2.8 XR II LD have the same Filter thread size of 67mm.
Below are links to the 67mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Canon 18-135mm F3.5-5.6 IS has the Canon EF-S lens mount whereas the Tamron 17-50mm f2.8 XR II LD has the Canon EF 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-S Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF Mount.
Canon 18-135mm F3.5-5.6 IS is also available in 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
Canon 18-135mm F3.5-5.6 IS has a focal range of 18-135mm and
7.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-216mm when used on a APS-C / DX format camera.
On the other hand, the 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.
