The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica Summarit-M 50mm f2.5 and the Carl Zeiss Planar T2/50 ZM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Carl Zeiss Planar T2/50 ZM is the longer of the two lenses at 68mm. The Leica Summarit-M 50mm f2.5 with a length of 33mm, is 35mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 52mm.
The 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.
Below you can find the dimension and weight table of the Standard Prime Lenses in Leica M Mount for size comparison purposes.
Standard Prime Lenses in Leica M Mount for Size Comparison
Lens Mounts
Both the Leica Summarit-M 50mm f2.5 and the Carl Zeiss Planar T2/50 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.
Focal Range
Both lenses have the same focal range of 50mm but while Leica Summarit-M 50mm f2.5 has the fastest aperture of F2.5, the Carl Zeiss Planar T2/50 ZM's widest aperture value is F2.0.