The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Viltrox AF 16mm f1.8 L and the Sigma 20mm F2 DG DN C 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. Viltrox AF 16mm f1.8 L is the longer of the two lenses at 103mm. The Sigma 20mm F2 DG DN C with a length of 72mm, is 31mm shorter. Besides being longer, the Viltrox AF 16mm f1.8 L also has a larger diameter of 85mm compared to the Sigma 20mm F2 DG DN C's 70mm 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 F2 DG DN C weighs 370g, 32% (180g) lighter than the Viltrox AF 16mm f1.8 L's weight of 550g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Leica L Mount for size comparison purposes.
Ultra-Wideangle Lenses in Leica L Mount for Size Comparison
Filter Threads
The Viltrox AF 16mm f1.8 L has a filter size of 77mm whereas the Sigma 20mm F2 DG DN C has a 62mm 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 Viltrox AF 16mm f1.8 L:
And these are the 62mm filters that we recommend for the Sigma 20mm F2 DG DN C:
Lens Mounts
Both the Viltrox AF 16mm f1.8 L and the Sigma 20mm F2 DG DN C has the same Leica L lens mount. Some of the latest released cameras that are compatible with the Leica L lenses are Nikon ZR, Nikon Z5 II and RED Komodo-X 6K Z.
Sigma 20mm F2 DG DN C is also available in Sony E mount.
Focal Range
Viltrox AF 16mm f1.8 L is a prime lens with fixed focal lenght of 16mm.
On the other hand, the Sigma 20mm F2 DG DN C 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.