The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony 16-35mm F2.8 ZA SSM II and the Sigma 20mm F1.8 EX DG RF 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. Sony 16-35mm F2.8 ZA SSM II is the longer of the two lenses at 114mm. The Sigma 20mm F1.8 EX DG RF with a length of 90mm, is 24mm shorter. On the other hand, the Sigma 20mm F1.8 EX DG RF has a larger diameter of 89mm compared to the Sony 16-35mm F2.8 ZA SSM II's 83mm 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. Sigma 20mm F1.8 EX DG RF weighs 520g, 40% (352g) lighter than the Sony 16-35mm F2.8 ZA SSM II's weight of 872g.
Filter Threads
The Sony 16-35mm F2.8 ZA SSM II has a filter size of 77mm whereas the Sigma 20mm F1.8 EX DG RF has a 82mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Sony 16-35mm F2.8 ZA SSM II:
And these are the 82mm filters that we recommend for the Sigma 20mm F1.8 EX DG RF:
Lens Mounts
Both the Sony 16-35mm F2.8 ZA SSM II and the Sigma 20mm F1.8 EX DG RF 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 20mm F1.8 EX DG RF is also available in Canon EF , Nikon F (DX), Pentax KAF and Sigma SA mounts.
Focal Range
Sony 16-35mm F2.8 ZA SSM II has a focal range of 16-35mm and
2.2X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
24 - 52.5mm.
On the other hand, the Sigma 20mm F1.8 EX DG RF 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.