The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 14mm F1.8 GM and the Sigma 19mm F2.8 DN 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. Sigma 19mm F2.8 DN weighs 140g, 69% (320g) lighter than the Sony FE 14mm F1.8 GM's weight of 460g.
Lens Mounts
Both the Sony FE 14mm F1.8 GM and the Sigma 19mm F2.8 DN has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A9 III, Sony A7C Mark II and Sony A7CR.
Sigma 19mm F2.8 DN is also available in Micro Four Thirds mount.
Focal Range
Sony FE 14mm F1.8 GM is a prime lens with fixed focal lenght of 14mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
21mm.
On the other hand, the Sigma 19mm F2.8 DN is a prime lens with fixed focal lenght of 19mm which has an effective (full-frame 35mm equivalent) focal range of 28.5mm when used on a APS-C / DX format camera.