The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 40mm F1.4 DG HSM A and the Sony E 50mm F1.8 OSS for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 40mm F1.4 DG HSM A is the longer of the two lenses at 131mm. The Sony E 50mm F1.8 OSS with a length of 62mm is 69mm shorter. Besides being longer, the Sigma 40mm F1.4 DG HSM A also has a larger diameter of 88mm compared to Sony E 50mm F1.8 OSS's 62mm diameter.
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.
Below you can find the dimension and weight table of the 'Standard Prime Lenses in Sony E Mount for size comparison purposes.
Standard Prime Lenses in Sony E Mount for Size Comparison
Both Sigma 40mm F1.4 DG HSM A and Sony E 50mm 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 40mm F1.4 DG HSM A is also available in Canon EF , Nikon F (FX), Sigma SA and Leica L mounts.
Sigma 40mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 40mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 60mm.
Sony E 50mm F1.8 OSS is a prime lens with fixed focal lenght of 50mm which has a 35mm equivalent focal range of 60mm when used on a APS-C / DX format camera.