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 200-500mm F2.8 EX DG 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 200-500mm F2.8 EX DG is the longer of the two lenses at 726mm. The Tamron 18-400mm F3.5-6.3 VC with a length of 124mm, is 602mm shorter. Besides being longer, the Sigma 200-500mm F2.8 EX DG also has a larger diameter of 237mm compared to the Tamron 18-400mm F3.5-6.3 VC's 79mm 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 18-400mm F3.5-6.3 VC weighs 710g, which means it is 14990g (95%) lighter than the Sigma 200-500mm F2.8 EX DG which has a weight of 15700g.
Filter Threads
Both the Tamron 18-400mm F3.5-6.3 VC and the Sigma 200-500mm F2.8 EX DG 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 Nikon F (DX) lens mount whereas the Sigma 200-500mm F2.8 EX DG has the Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount and Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount.
Tamron 18-400mm F3.5-6.3 VC is also available in the Canon EF-S mount.
Sigma 200-500mm F2.8 EX DG is also available in Sigma SA and Canon EF 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
27-600mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 200-500mm F2.8 EX DG has a focal range of 200-500mm and 2.5X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 300 - 750mm.
