The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 10-24mm f3.5-4.5 II LD and the Sigma 12-24mm F4.5-5.6 EX DG HSM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Sigma 12-24mm F4.5-5.6 EX DG HSM is the longer of the two lenses at 103mm. The Tamron 10-24mm f3.5-4.5 II LD with a length of 84mm, is 19mm shorter. Besides being longer, the Sigma 12-24mm F4.5-5.6 EX DG HSM also has a larger diameter of 87mm compared to the Tamron 10-24mm f3.5-4.5 II LD's 83mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Tamron 10-24mm f3.5-4.5 II LD weighs 406g, which means it is 194g (32%) lighter than the Sigma 12-24mm F4.5-5.6 EX DG HSM which has a weight of 600g.
Below you can find the dimension and weight table of the Wideangle Zoom Lenses in Sony Alpha Mount for size comparison purposes.
Wideangle Zoom Lenses in Sony Alpha Mount for Size Comparison
Lens Mounts
Both the Tamron 10-24mm f3.5-4.5 II LD and the Sigma 12-24mm F4.5-5.6 EX DG HSM has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A68, Sony A77 II and Sony A58.
Tamron 10-24mm f3.5-4.5 II LD is also available in Canon EF , Nikon F (DX), Pentax KAF and Canon EF mounts.
Sigma 12-24mm F4.5-5.6 EX DG HSM is also available in Canon EF , Pentax KAF, Sigma SA and Nikon F (FX) mounts.
Focal Range
Tamron 10-24mm f3.5-4.5 II LD has a focal range of 10-24mm and 2.4X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 15-36mm when used on a APS-C / DX format camera. Sigma 12-24mm F4.5-5.6 EX DG HSM 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.