The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 18-300mm F3.5-6.3 and the Tamron 18-400mm F3.5-6.3 VC 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 18-300mm F3.5-6.3 is the longer of the two lenses at 126mm. The Tamron 18-400mm F3.5-6.3 VC with a length of 124mm, is 2mm shorter. On the other hand, the Tamron 18-400mm F3.5-6.3 VC has a larger diameter of 79mm compared to the Tamron 18-300mm F3.5-6.3's 76mm 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 18-300mm F3.5-6.3 weighs 620g, which means it is 90g (12%) lighter than the Tamron 18-400mm F3.5-6.3 VC which has a weight of 710g.
Filter Threads
The Tamron 18-300mm F3.5-6.3 has a filter size of 67mm whereas the Tamron 18-400mm F3.5-6.3 VC 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 18-300mm F3.5-6.3:
And these are the 72mm filters that we recommend for the Tamron 18-400mm F3.5-6.3 VC:
Lens Mounts
The Tamron 18-300mm F3.5-6.3 has the Canon RF lens mount whereas the Tamron 18-400mm F3.5-6.3 VC has the Canon EF-S lens mount. Some of the latest released cameras that are compatible with these mounts are Canon R50 V, Canon R100 and Canon R50 for the Canon RF Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF-S Mount.
Tamron 18-300mm F3.5-6.3 is also available in the Nikon Z mount.
Tamron 18-400mm F3.5-6.3 VC is also available in Nikon F (DX) mount.
Focal Range
Tamron 18-300mm F3.5-6.3 has a focal range of 18-300mm and
16.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-480mm when used on a APS-C / DX format camera.
On the other hand, the 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.