The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 12mm f1.4 and the Tamron 20mm F2.8 Di III OSD M1:2 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. Sigma 12mm f1.4 is the longer of the two lenses at 69mm. The Tamron 20mm F2.8 Di III OSD M1:2 with a length of 64mm, is 5mm shorter. On the other hand, the Tamron 20mm F2.8 Di III OSD M1:2 has a larger diameter of 73mm compared to the Sigma 12mm f1.4's 68mm 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 20mm F2.8 Di III OSD M1:2 weighs 220g, 2% (5g) lighter than the Sigma 12mm f1.4's weight of 225g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Sony E Mount for size comparison purposes.
Ultra-Wideangle Lenses in Sony E Mount for Size Comparison
Filter Threads
The Sigma 12mm f1.4 has a filter size of 62mm whereas the Tamron 20mm F2.8 Di III OSD M1:2 has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 62mm filters that we recommend you to consider for the Sigma 12mm f1.4:
And these are the 67mm filters that we recommend for the Tamron 20mm F2.8 Di III OSD M1:2:
Lens Mounts
Both the Sigma 12mm f1.4 and the Tamron 20mm F2.8 Di III OSD M1:2 has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony ZV-E10 II, Sony A6700 and Sony FX30.
Sigma 12mm f1.4 is also available in the Fujifilm X and Canon RF mounts.
Focal Range
Sigma 12mm f1.4 is a prime lens with fixed focal lenght of 12mm which has an effective (full-frame 35mm equivalent) focal range of
18mm when used on a APS-C / DX format camera.
On the other hand, the Tamron 20mm F2.8 Di III OSD M1:2 is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 30mm.
