The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony DT 11-18mm F4.5-5.6 and the Sigma 10-20mm F4-5.6 EX DC HSM for their suitability to various photography scenarios:
Size and Weight Comparison
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. Sony DT 11-18mm F4.5-5.6 weighs 360g, which means it is 110g (23%) lighter than the Sigma 10-20mm F4-5.6 EX DC HSM which has a weight of 470g.
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 Sony DT 11-18mm F4.5-5.6 and 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 A68, Sony A77 II and Sony A58.
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
Sony DT 11-18mm F4.5-5.6 has a focal range of 11-18mm and 1.6X zoom ratio which has a 35mm equivalent focal range of 16.5-27mm when used on a APS-C / DX format camera. Sigma 10-20mm F4-5.6 EX DC HSM has a focal range of 10-20mm and 2.0X zoom ratio which has a 35mm equivalent focal range of 15-30mm when used on a APS-C / DX format camera.