The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Voigtlander 21mm F1.8 Ultron and the Carl Zeiss Distagon T4/18 ZM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Voigtlander 21mm F1.8 Ultron is the longer of the two lenses at 92mm. The Carl Zeiss Distagon T4/18 ZM with a length of 71mm is 21mm shorter. On the other hand, the Carl Zeiss Distagon T4/18 ZM has a larger diameter of 65mm compared to Voigtlander 21mm F1.8 Ultron's 62mm 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. Carl Zeiss Distagon T4/18 ZM weighs 350g, 15% (62g) lighter than the Voigtlander 21mm F1.8 Ultron's weight of 412g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Leica M Mount for size comparison purposes.
Wideangle Prime Lenses in Leica M Mount for Size Comparison
Both Voigtlander 21mm F1.8 Ultron and Carl Zeiss Distagon T4/18 ZM has the same Leica M lens mount. Some of the latest released cameras that are compatible with the Leica M lenses are Leica M11, Leica M10 and Leica M Typ 262.
Voigtlander 21mm F1.8 Ultron is a prime lens with fixed focal lenght of 21mm. Carl Zeiss Distagon T4/18 ZM is a prime lens with fixed focal lenght of 18mm.