The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 20mm F1.4 DG HSM A and the Zeiss Milvus 18mm F2.8 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 20mm F1.4 DG HSM A is the longer of the two lenses at 130mm. The Zeiss Milvus 18mm F2.8 with a length of 93mm, is 37mm shorter. Besides being longer, the Sigma 20mm F1.4 DG HSM A also has a larger diameter of 91mm compared to the Zeiss Milvus 18mm F2.8's 73mm 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. Zeiss Milvus 18mm F2.8 weighs 721g, 24% (229g) lighter than the Sigma 20mm F1.4 DG HSM A's weight of 950g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Canon EF Mount for size comparison purposes.
Ultra-Wideangle Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both the Sigma 20mm F1.4 DG HSM A and the Zeiss Milvus 18mm F2.8 has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Sigma 20mm F1.4 DG HSM A is also available in Nikon F (FX) , Sigma SA and Leica L mounts.
Zeiss Milvus 18mm F2.8 is also available in Nikon F (FX) mount.
Focal Range
Sigma 20mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
32mm.
On the other hand, the Zeiss Milvus 18mm F2.8 is a prime lens with fixed focal lenght of 18mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 28.8mm.