The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 18-200mm F3.5-6.3 Di II VC and the Canon 28-300mm f3.5-5.6L 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 28-300mm f3.5-5.6L IS USM is the longer of the two lenses at 184mm. The Tamron 18-200mm F3.5-6.3 Di II VC with a length of 97mm is 87mm shorter. Besides being longer, the Canon 28-300mm f3.5-5.6L IS USM also has a larger diameter of 92mm compared to Tamron 18-200mm F3.5-6.3 Di II VC's 75mm 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 18-200mm F3.5-6.3 Di II VC weighs 400g, which means it is 1270g (76%) lighter than the Canon 28-300mm f3.5-5.6L IS USM which has a weight of 1670g.
Below you can find the dimension and weight table of the 'SuperZoom Lenses in Canon EF Mount for size comparison purposes.
SuperZoom Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both Tamron 18-200mm F3.5-6.3 Di II VC and Canon 28-300mm f3.5-5.6L IS USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon T8i, Canon 90D and Canon SL3.
Tamron 18-200mm F3.5-6.3 Di II VC is also available in Nikon F (DX) and Sony Alpha mounts.
Focal Range
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. Canon 28-300mm f3.5-5.6L IS USM has a focal range of 28-300mm and 10.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 44.8 - 480mm.