The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica SL 50mm f2 ASPH and the Sigma 56mm F1.4 DC DN C for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Leica SL 50mm f2 ASPH is the longer of the two lenses at 83mm. The Sigma 56mm F1.4 DC DN C with a length of 60mm, is 23mm shorter. Besides being longer, the Leica SL 50mm f2 ASPH also has a larger diameter of 75mm compared to the Sigma 56mm F1.4 DC DN C's 67mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Sigma 56mm F1.4 DC DN C weighs 280g, 30% (122g) lighter than the Leica SL 50mm f2 ASPH's weight of 402g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Leica L Mount for size comparison purposes.
Standard Lenses in Leica L Mount for Size Comparison
Filter Threads
The Leica SL 50mm f2 ASPH has a filter size of 67mm whereas the Sigma 56mm F1.4 DC DN C has a 55mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Leica SL 50mm f2 ASPH:
And these are the 55mm filters that we recommend for the Sigma 56mm F1.4 DC DN C:
Lens Mounts
Both the Leica SL 50mm f2 ASPH and the 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 Leica SL3, Panasonic S5 II and Panasonic S5 II X.
Sigma 56mm F1.4 DC DN C is also available in Micro Four Thirds and Sony E mounts.
Focal Range
Leica SL 50mm f2 ASPH is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
75mm.
On the other hand, the Sigma 56mm F1.4 DC DN C is a prime lens with fixed focal lenght of 56mm which has an effective (full-frame 35mm equivalent) focal range of 84mm when used on a APS-C / DX format camera.