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 18-200mm F3.5-6.3 Di II VC 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 18-200mm F3.5-6.3 Di II VC is the longer of the two lenses at 97mm. The Canon 18-135mm F3.5-5.6 IS with a length of 96mm, is 1mm shorter. On the other hand, the Canon 18-135mm F3.5-5.6 IS has a larger diameter of 77mm compared to the Tamron 18-200mm F3.5-6.3 Di II VC's 75mm diameter.
tt
Below you can find a scaled side-by-side image of Canon 18-135mm F3.5-5.6 IS and Tamron 18-200mm F3.5-6.3 Di II VC to get a better idea of how their sizes compare in real life.
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 18-200mm F3.5-6.3 Di II VC weighs 400g, 22% (115g) lighter than the Canon 18-135mm F3.5-5.6 IS's weight of 515g.
Filter Threads
The Canon 18-135mm F3.5-5.6 IS has a filter size of 67mm whereas the Tamron 18-200mm F3.5-6.3 Di II VC has a 62mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Canon 18-135mm F3.5-5.6 IS:
And these are the 62mm filters that we recommend for the Tamron 18-200mm F3.5-6.3 Di II VC:
Lens Mounts
The Canon 18-135mm F3.5-5.6 IS has the Canon EF-S lens mount whereas the Tamron 18-200mm F3.5-6.3 Di II VC 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 Canon EF-S mount.
Tamron 18-200mm F3.5-6.3 Di II VC is also available in Nikon F (DX) and Sony Alpha 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 18-200mm F3.5-6.3 Di II VC has a focal range of 18-200mm and 11.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 28.8-320mm when used on a APS-C / DX format camera.