The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 100-400mm F4.5-6.3 Di VC USD and the Sigma 18-300 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 100-400mm F4.5-6.3 Di VC USD is the longer of the two lenses at 199mm. The Sigma 18-300 F3.5-6.3 DC OS HSM with a length of 102mm, is 97mm shorter. Besides being longer, the Tamron 100-400mm F4.5-6.3 Di VC USD also has a larger diameter of 86mm compared to the Sigma 18-300 F3.5-6.3 DC OS HSM'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. Sigma 18-300 F3.5-6.3 DC OS HSM weighs 585g, 48% (550g) lighter than the Tamron 100-400mm F4.5-6.3 Di VC USD's weight of 1135g.
Filter Threads
The Tamron 100-400mm F4.5-6.3 Di VC USD has a filter size of 67mm whereas the Sigma 18-300 F3.5-6.3 DC OS HSM has a 72mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Tamron 100-400mm F4.5-6.3 Di VC USD:
And these are the 72mm filters that we recommend for the Sigma 18-300 F3.5-6.3 DC OS HSM:
Lens Mounts
The Tamron 100-400mm F4.5-6.3 Di VC USD has the Nikon F (FX) lens mount whereas the Sigma 18-300 F3.5-6.3 DC OS HSM has the Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount and Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount.
Tamron 100-400mm F4.5-6.3 Di VC USD is also available in the Canon EF mount.
Sigma 18-300 F3.5-6.3 DC OS HSM is also available in Canon EF , Pentax KAF3, Sigma SA and Sony Alpha mounts.
Focal Range
Tamron 100-400mm F4.5-6.3 Di VC USD has a focal range of 100-400mm and
4.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
150 - 600mm.
On the other hand, the Sigma 18-300 F3.5-6.3 DC OS HSM has a focal range of 18-300mm and 16.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-450mm when used on a APS-C / DX format camera.
