The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica APO-Summicron-SL 35mm F2 ASPH and the Sigma 40mm F1.4 DG HSM A 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 Leica APO-Summicron-SL 35mm F2 ASPH with a length of 102mm is 29mm shorter. Besides being longer, the Sigma 40mm F1.4 DG HSM A also has a larger diameter of 88mm compared to Leica APO-Summicron-SL 35mm F2 ASPH's 73mm 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.
Lens Mounts
Both Leica APO-Summicron-SL 35mm F2 ASPH and Sigma 40mm 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 Panasonic S5 II, Panasonic S5 II X and Sigma fp L.
Sigma 40mm F1.4 DG HSM A is also available in Canon EF , Nikon F (FX), Sigma SA and Sony E mounts.
Focal Range
Leica APO-Summicron-SL 35mm F2 ASPH is a prime lens with fixed focal lenght of 35mm. Sigma 40mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 40mm.