The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica Summaron-M 28mm F5.6 and the Voigtlander 21mm F4 Color Skopar II 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. Voigtlander 21mm F4 Color Skopar II is the longer of the two lenses at 25mm. The Leica Summaron-M 28mm F5.6 with a length of 18mm, is 7mm shorter. Besides being longer, the Voigtlander 21mm F4 Color Skopar II also has a larger diameter of 55mm compared to the Leica Summaron-M 28mm F5.6's 51mm 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. Voigtlander 21mm F4 Color Skopar II weighs 136g, 17% (29g) lighter than the Leica Summaron-M 28mm F5.6's weight of 165g.
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 Summaron-M 28mm F5.6 has a filter size of 34mm whereas the Voigtlander 21mm F4 Color Skopar II has a 39mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 34mm filters that we recommend you to consider for the Leica Summaron-M 28mm F5.6:
And these are the 39mm filters that we recommend for the Voigtlander 21mm F4 Color Skopar II:
Lens Mounts
Both the Leica Summaron-M 28mm F5.6 and the Voigtlander 21mm F4 Color Skopar II 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 Summaron-M 28mm F5.6 is a prime lens with fixed focal lenght of 28mm.
On the other hand, the Voigtlander 21mm F4 Color Skopar II is a prime lens with fixed focal lenght of 21mm.