There are three versions of the first-generation Summicron 90mm f/2 with the same optical design, differing mainly in appearance. Also, they are all very well made, focus smoothly, and they have been defined as high-end lenses from the start. These lenses are mainly used by professional photographers to take portraits and capture long distances. They have excellent optics and their only drawback is that they are too bulky.
The design of the built-in hood is very clever. I like this design very much. The mechanical design of the hood is also very good, and the push and pull damping is perfect. I have not seen any other lens with such perfect damping, including later Leica lenses.
For the Leica m camera system, there are two major problems with using a 90mm lens: the viewing range is too small and the focusing speed is too slow. Another big problem is hand tremors. The safety shutter of a 90mm lens is 1/100s. Shutter speeds below this are prone to hand shake. This greatly reduces its frequency of use.
Maximum aperture: 1: 2 Angle: 270 Minimum distance: 100cm Filter: E48