The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony 20mm F2.8 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 a crucial factor to consider when comparing two lenses. Sigma 10-20mm F4-5.6 EX DC HSM is the longer of the two lenses at 81mm. The Sony 20mm F2.8 with a length of 54mm, is 27mm shorter. Besides being longer, the Sigma 10-20mm F4-5.6 EX DC HSM also has a larger diameter of 84mm compared to the Sony 20mm F2.8's 78mm 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. Sony 20mm F2.8 weighs 285g, which means it is 185g (39%) lighter than the Sigma 10-20mm F4-5.6 EX DC HSM which has a weight of 470g.
Filter Threads
The Sony 20mm F2.8 has a filter size of 72mm whereas the Sigma 10-20mm F4-5.6 EX DC HSM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 72mm filters that we recommend you to consider for the Sony 20mm F2.8:
And these are the 77mm filters that we recommend for the Sigma 10-20mm F4-5.6 EX DC HSM:
Lens Mounts
Both the Sony 20mm F2.8 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.
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 20mm F2.8 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.
On the other hand, the 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.
