The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 20mm F2 DG DN C and the Leica APO-SL 28mm F2 ASPH 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 APO-SL 28mm F2 ASPH is the longer of the two lenses at 102mm. The Sigma 20mm F2 DG DN C with a length of 72mm, is 30mm shorter. Besides being longer, the Leica APO-SL 28mm F2 ASPH also has a larger diameter of 73mm compared to the Sigma 20mm F2 DG DN C's 70mm diameter.
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Below you can find a scaled side-by-side image of Sigma 20mm F2 DG DN C and Leica APO-SL 28mm F2 ASPH to get a better idea of how their sizes compare in real life.
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 20mm F2 DG DN C weighs 370g, which means it is 330g (47%) lighter than the Leica APO-SL 28mm F2 ASPH which has a weight of 700g.
Filter Threads
The Sigma 20mm F2 DG DN C has a filter size of 62mm whereas the Leica APO-SL 28mm F2 ASPH has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 62mm filters that we recommend you to consider for the Sigma 20mm F2 DG DN C:
And these are the 67mm filters that we recommend for the Leica APO-SL 28mm F2 ASPH:
Lens Mounts
Both the Sigma 20mm F2 DG DN C and the Leica APO-SL 28mm F2 ASPH 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 20mm F2 DG DN C is also available in Sony E mount.
Focal Range
Sigma 20mm F2 DG DN C is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
30mm.
On the other hand, the Leica APO-SL 28mm F2 ASPH is a prime lens with fixed focal lenght of 28mm.