The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica Summarit-M 90mm f2.5 and the Carl Zeiss Sonnar T2/85 ZM 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. Carl Zeiss Sonnar T2/85 ZM is the longer of the two lenses at 100mm. The Leica Summarit-M 90mm f2.5 with a length of 67mm, is 33mm shorter. Besides being longer, the Carl Zeiss Sonnar T2/85 ZM also has a larger diameter of 70mm compared to the Leica Summarit-M 90mm f2.5's 55mm 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. Leica Summarit-M 90mm f2.5 weighs 360g, which means it is 140g (28%) lighter than the Carl Zeiss Sonnar T2/85 ZM which has a weight of 500g.
Filter Threads
The Leica Summarit-M 90mm f2.5 has a filter size of 46mm whereas the Carl Zeiss Sonnar T2/85 ZM has a 58mm 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 Summarit-M 90mm f2.5:
And these are the 58mm filters that we recommend for the Carl Zeiss Sonnar T2/85 ZM:
Lens Mounts
Both the Leica Summarit-M 90mm f2.5 and the Carl Zeiss Sonnar T2/85 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 Monochrome, Leica M11 and Leica M10.
Focal Range
Leica Summarit-M 90mm f2.5 is a prime lens with fixed focal lenght of 90mm.
On the other hand, the Carl Zeiss Sonnar T2/85 ZM is a prime lens with fixed focal lenght of 85mm.