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 12-24mm 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 12-24mm F2.8 GM is the longer of the two lenses at 137mm. The Tamron 11-20mm F2.8 Di III-A with a length of 86mm, is 51mm shorter. Besides being longer, the Sony 12-24mm F2.8 GM also has a larger diameter of 98mm compared to the Tamron 11-20mm F2.8 Di III-A's 73mm diameter.
Below you can find a scaled side-by-side image of Tamron 11-20mm F2.8 Di III-A and Sony 12-24mm 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 512g (60%) lighter than the Sony 12-24mm F2.8 GM which has a weight of 847g.
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
Both the Tamron 11-20mm F2.8 Di III-A and the Sony 12-24mm 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.
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 12-24mm F2.8 GM has a focal range of 12-24mm and 2.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 18 - 36mm.