The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 20mm F1.8 G and the Leica Tri-Elmar-M 16-18-21mm f4 ASPH for their suitability to various photography scenarios:
Size and Weight Comparison
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. Leica Tri-Elmar-M 16-18-21mm f4 ASPH weighs 335g, 10% (38g) lighter than the Sony FE 20mm F1.8 G's weight of 373g.
Lens Mounts
The Sony FE 20mm F1.8 G has the Sony E lens mount whereas the Leica Tri-Elmar-M 16-18-21mm f4 ASPH has the Leica M lens mount. Some of the latest released cameras that are compatible with these mounts are Sony A9 III, Sony A7C Mark II and Sony A7CR for the Sony E Mount and Leica M11 Monochrome, Leica M11 and Leica M10 for the Leica M Mount.
Focal Range
Sony FE 20mm F1.8 G 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 Leica Tri-Elmar-M 16-18-21mm f4 ASPH has a focal range of 16-21mm and 1.3X zoom ratio .