The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 11-20mm F2.8 Di III-A and the Sony FE 16-35mm F2.8 GM 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 16-35mm F2.8 GM is the longer of the two lenses at 122mm. The Tamron 11-20mm F2.8 Di III-A with a length of 86mm, is 36mm shorter. Besides being longer, the Sony FE 16-35mm F2.8 GM also has a larger diameter of 89mm compared to the Tamron 11-20mm F2.8 Di III-A's 73mm diameter.
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Below you can find a scaled side-by-side image of Tamron 11-20mm F2.8 Di III-A and Sony FE 16-35mm F2.8 GM 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 11-20mm F2.8 Di III-A weighs 335g, which means it is 345g (50%) lighter than the Sony FE 16-35mm F2.8 GM which has a weight of 680g.
Below you can find the dimension and weight table of the Wideangle Zoom Lenses in Sony E Mount for size comparison purposes.
Ultra-Wideangle Lenses in Sony E Mount for Size Comparison
Filter Threads
The Tamron 11-20mm F2.8 Di III-A has a filter size of 67mm whereas the Sony FE 16-35mm F2.8 GM has a 82mm 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 11-20mm F2.8 Di III-A:
And these are the 82mm filters that we recommend for the Sony FE 16-35mm F2.8 GM:
Lens Mounts
Both the Tamron 11-20mm F2.8 Di III-A and the Sony FE 16-35mm F2.8 GM has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A6700, Sony FX30 and Sony ZV-E10.
Tamron 11-20mm F2.8 Di III-A is also available in Fujifilm X mount.
Focal Range
Tamron 11-20mm F2.8 Di III-A has a focal range of 11-20mm and
1.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
16.5-30mm when used on a APS-C / DX format camera.
On the other hand, the Sony FE 16-35mm F2.8 GM has a focal range of 16-35mm and 2.2X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 24 - 52.5mm.