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 Sigma 19mm F2.8 EX DN 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 FE 20mm F1.8 G is the longer of the two lenses at 85mm. The Sigma 19mm F2.8 EX DN with a length of 46mm, is 39mm shorter. Besides being longer, the Sony FE 20mm F1.8 G also has a larger diameter of 74mm compared to the Sigma 19mm F2.8 EX DN's 61mm 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 19mm F2.8 EX DN weighs 140g, 62% (233g) lighter than the Sony FE 20mm F1.8 G's weight of 373g.
Filter Threads
The Sony FE 20mm F1.8 G has a filter size of 67mm whereas the Sigma 19mm F2.8 EX DN has a 46mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Sony FE 20mm F1.8 G:
And these are the 46mm filters that we recommend for the Sigma 19mm F2.8 EX DN:
Lens Mounts
The Sony FE 20mm F1.8 G has the Sony E lens mount whereas the Sigma 19mm F2.8 EX DN has the Micro Four Thirds 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 , and for the Micro Four Thirds Mount.
Sigma 19mm F2.8 EX DN is also available in Sony E 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 Sigma 19mm F2.8 EX 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.