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 DN A and the Sony E 35mm F1.8 OSS for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Sigma 20mm F1.4 DG DN A is the longer of the two lenses at 111mm. The Sony E 35mm F1.8 OSS with a length of 45mm, is 66mm shorter. Besides being longer, the Sigma 20mm F1.4 DG DN A also has a larger diameter of 88mm compared to the Sony E 35mm F1.8 OSS's 63mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Sony E 35mm F1.8 OSS weighs 155g, 75% (480g) lighter than the Sigma 20mm F1.4 DG DN A's weight of 635g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Sony E Mount for size comparison purposes.
Wideangle Prime Lenses in Sony E Mount for Size Comparison
Both the Sigma 20mm F1.4 DG DN A and the Sony E 35mm F1.8 OSS has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A7R V, Sony FX30 and Sony A7 IV.
Sigma 20mm F1.4 DG DN A is also available in Leica L mount.
Sigma 20mm F1.4 DG DN A 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 36mm.
Sony E 35mm F1.8 OSS is a prime lens with fixed focal lenght of 35mm which has an effective (full-frame 35mm equivalent) focal range of 52.5mm when used on a APS-C / DX format camera.