The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 15-30mm f2.8 VC USD and the Sigma 10-20mm F4-5.6 EX DC 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. Tamron 15-30mm f2.8 VC USD is the longer of the two lenses at 145mm. The Sigma 10-20mm F4-5.6 EX DC HSM with a length of 81mm, is 64mm shorter. Besides being longer, the Tamron 15-30mm f2.8 VC USD also has a larger diameter of 98mm compared to the Sigma 10-20mm F4-5.6 EX DC HSM's 84mm 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. Sigma 10-20mm F4-5.6 EX DC HSM weighs 470g, 57% (630g) lighter than the Tamron 15-30mm f2.8 VC USD's weight of 1100g.
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 15-30mm f2.8 VC USD and the Sigma 10-20mm F4-5.6 EX DC HSM has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Tamron 15-30mm f2.8 VC USD is also available in Canon EF and Nikon F (FX) mounts.
Sigma 10-20mm F4-5.6 EX DC HSM is also available in Canon EF , Four Thirds, Pentax KAF, Sigma SA and Nikon F (DX) mounts.
Focal Range
Tamron 15-30mm f2.8 VC USD has a focal range of 15-30mm 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 22.5 - 45mm.
Sigma 10-20mm F4-5.6 EX DC HSM has a focal range of 10-20mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 15-30mm when used on a APS-C / DX format camera.