The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron AF 18-270mm f3.5-6.3 II VC LD and the Sigma 50-500mm F4.5-6.3 DG OS HSM 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. Sigma 50-500mm F4.5-6.3 DG OS HSM is the longer of the two lenses at 219mm. The Tamron AF 18-270mm f3.5-6.3 II VC LD with a length of 101mm, is 118mm shorter. Besides being longer, the Sigma 50-500mm F4.5-6.3 DG OS HSM also has a larger diameter of 104mm compared to the Tamron AF 18-270mm f3.5-6.3 II VC LD's 80mm 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 AF 18-270mm f3.5-6.3 II VC LD weighs 560g, which means it is 1410g (71%) lighter than the Sigma 50-500mm F4.5-6.3 DG OS HSM which has a weight of 1970g.
Below you can find the dimension and weight table of the SuperZoom Lenses in Canon EF Mount for size comparison purposes.
Super Telephoto Lenses in Canon EF Mount for Size Comparison
Filter Threads
The Tamron AF 18-270mm f3.5-6.3 II VC LD has a filter size of 72mm whereas the Sigma 50-500mm F4.5-6.3 DG OS HSM has a 95mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 72mm filters that we recommend you to consider for the Tamron AF 18-270mm f3.5-6.3 II VC LD:
And these are the 95mm filters that we recommend for the Sigma 50-500mm F4.5-6.3 DG OS HSM:
Lens Mounts
Both the Tamron AF 18-270mm f3.5-6.3 II VC LD and the Sigma 50-500mm F4.5-6.3 DG 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 AF 18-270mm f3.5-6.3 II VC LD is also available in Nikon F (DX) mount.
Sigma 50-500mm F4.5-6.3 DG OS HSM is also available in Pentax KAF3 , Sony Alpha, Sigma SA and Nikon F (FX) mounts.
Focal Range
Tamron AF 18-270mm f3.5-6.3 II VC LD 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 50-500mm F4.5-6.3 DG OS HSM has a focal range of 50-500mm and 10.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 80 - 800mm.