The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 70-300 F4.5-6.3 Di III and the Sony FE 100-400mm F4.5-5.6 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. Sony FE 100-400mm F4.5-5.6 is the longer of the two lenses at 205mm. The Tamron 70-300 F4.5-6.3 Di III with a length of 148mm, is 57mm shorter. Besides being longer, the Sony FE 100-400mm F4.5-5.6 also has a larger diameter of 94mm compared to the Tamron 70-300 F4.5-6.3 Di III's 77mm diameter.
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Below you can find a scaled side-by-side image of Tamron 70-300 F4.5-6.3 Di III and Sony FE 100-400mm F4.5-5.6 to get a better idea of how their sizes compare in real life.
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 70-300 F4.5-6.3 Di III weighs 545g, which means it is 850g (60%) lighter than the Sony FE 100-400mm F4.5-5.6 which has a weight of 1395g.
Filter Threads
The Tamron 70-300 F4.5-6.3 Di III has a filter size of 67mm whereas the Sony FE 100-400mm F4.5-5.6 has a 77mm 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 70-300 F4.5-6.3 Di III:
And these are the 77mm filters that we recommend for the Sony FE 100-400mm F4.5-5.6:
Lens Mounts
Both the Tamron 70-300 F4.5-6.3 Di III and the Sony FE 100-400mm F4.5-5.6 has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A9 III, Sony A7C Mark II and Sony A7CR.
Focal Range
Tamron 70-300 F4.5-6.3 Di III has a focal range of 70-300mm and
4.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
105 - 450mm.
On the other hand, the Sony FE 100-400mm F4.5-5.6 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.