The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 18-270mm f3.5-6.3 II VC PZD and the Sigma 18-200mm f3.5-6.3 II DC OS HSM for their suitability to various photography scenarios:
Size and Weight Comparison
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 18-270mm f3.5-6.3 II VC PZD weighs 450g, which means it is 40g (8%) lighter than the Sigma 18-200mm f3.5-6.3 II DC OS HSM which has a weight of 490g.
Filter Threads
Both the Tamron 18-270mm f3.5-6.3 II VC PZD and the Sigma 18-200mm f3.5-6.3 II DC OS HSM have the same Filter thread size of 62mm.
Below are links to the 62mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Tamron 18-270mm f3.5-6.3 II VC PZD and the Sigma 18-200mm f3.5-6.3 II DC OS HSM 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 18-270mm f3.5-6.3 II VC PZD is also available in the Nikon F (DX) mount.
Sigma 18-200mm f3.5-6.3 II DC OS HSM is also available in Nikon F (DX) and Sigma SA mounts.
Focal Range
Tamron 18-270mm f3.5-6.3 II VC PZD has a focal range of 18-270mm and
15.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-432mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 18-200mm f3.5-6.3 II DC OS HSM 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.