Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 50mm F1.4 DG HSM A is the longer of the two lenses at 100mm. The Sigma 56mm F1.4 DC DN C with a length of 60mm is 40mm shorter. Besides being longer, the Sigma 50mm F1.4 DG HSM A also has a larger diameter of 85mm compared to Sigma 56mm F1.4 DC DN C's 67mm 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. Sigma 56mm F1.4 DC DN C weighs 280g, which means it is 535g (191%) lighter than the Sigma 50mm F1.4 DG HSM A which has a weight of 815g.
Below you can find the dimension and weight table of the 'Standard Prime Lenses in Leica L Mount for size comparison purposes.
Standard Prime Lenses in Leica L Mount for Size Comparison
Lens Mounts
Both Sigma 56mm F1.4 DC DN C and Sigma 50mm F1.4 DG HSM A has the same Leica L lens mount. Some of the latest released cameras that are compatible with the Leica L lenses are Leica TL2, Leica TL and Leica T Typ 701.
Sigma 56mm F1.4 DC DN C is also available in Micro Four Thirds and Sony E mounts.
Sigma 50mm F1.4 DG HSM A is also available in Canon EF , Sony Alpha, Sigma SA and Nikon F (FX) mounts.
Focal Range
Sigma 56mm F1.4 DC DN C is a prime lens with fixed focal lenght of 56mm which has a 35mm equivalent focal range of 84mm when used on a APS-C / DX format camera. Sigma 50mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 50mm.