The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 18-400mm F3.5-6.3 VC and the Sigma 18-250mm F3.5-6.3 DC 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. Tamron 18-400mm F3.5-6.3 VC is the longer of the two lenses at 124mm. The Sigma 18-250mm F3.5-6.3 DC OS HSM with a length of 101mm, is 23mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 79mm.
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. Sigma 18-250mm F3.5-6.3 DC OS HSM weighs 628g, 11% (82g) lighter than the Tamron 18-400mm F3.5-6.3 VC's weight of 710g.
Filter Threads
Both the Tamron 18-400mm F3.5-6.3 VC and the Sigma 18-250mm F3.5-6.3 DC OS HSM have the same Filter thread size of 72mm.
Below are links to the 72mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Tamron 18-400mm F3.5-6.3 VC has the Canon EF-S lens mount whereas the Sigma 18-250mm F3.5-6.3 DC OS HSM 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.
Tamron 18-400mm F3.5-6.3 VC is also available in the Nikon F (DX) mount.
Sigma 18-250mm F3.5-6.3 DC OS HSM is also available in Canon EF , Nikon F (DX), Pentax KAF3, Sony Alpha, Sigma SA, Nikon F (DX), Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Tamron 18-400mm F3.5-6.3 VC has a focal range of 18-400mm and
22.2X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-640mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 18-250mm F3.5-6.3 DC OS HSM has a focal range of 18-250mm and 13.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 28.8-400mm when used on a APS-C / DX format camera.
