Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Panasonic S 50mm F1.8 is the longer of the two lenses at 82mm. The Sigma 56mm F1.4 DC DN C with a length of 60mm is 22mm shorter. Besides being longer, the Panasonic S 50mm F1.8 also has a larger diameter of 74mm 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, 7% (20g) lighter than the Panasonic S 50mm F1.8's weight of 300g.
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
Both Panasonic S 50mm F1.8 and Sigma 56mm F1.4 DC DN C has the same Leica L lens mount. Some of the latest released cameras that are compatible with the Leica L lenses are Sigma fp L, Leica SL2-S and Panasonic S5.
Sigma 56mm F1.4 DC DN C is also available in Micro Four Thirds and Sony E mounts.
Panasonic S 50mm F1.8 is a prime lens with fixed focal lenght of 50mm. 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 75mm when used on a APS-C / DX format camera.