The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica Summilux-M 35mm f1.4 ASPH and the Leica Elmarit-M 21mm f2.8 ASPH for their suitability to various photography scenarios:
Size and Weight Comparison
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. Leica Elmarit-M 21mm f2.8 ASPH weighs 300g, 6% (20g) lighter than the Leica Summilux-M 35mm f1.4 ASPH's weight of 320g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Leica M Mount for size comparison purposes.
Wideangle Lenses in Leica M Mount for Size Comparison
Filter Threads
The Leica Summilux-M 35mm f1.4 ASPH has a filter size of 46mm whereas the Leica Elmarit-M 21mm f2.8 ASPH 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 46mm filters that we recommend you to consider for the Leica Summilux-M 35mm f1.4 ASPH:
And these are the 55mm filters that we recommend for the Leica Elmarit-M 21mm f2.8 ASPH:
Lens Mounts
Both the Leica Summilux-M 35mm f1.4 ASPH and the Leica Elmarit-M 21mm f2.8 ASPH has the same Leica M lens mount. Some of the latest released cameras that are compatible with the Leica M lenses are Leica M11 Monochrome, Leica M11 and Leica M10.
Focal Range
Leica Summilux-M 35mm f1.4 ASPH is a prime lens with fixed focal lenght of 35mm.
On the other hand, the Leica Elmarit-M 21mm f2.8 ASPH is a prime lens with fixed focal lenght of 21mm.