I picked this lens up a few months ago for $400 off ebay- had some internal Haze. I got some tips for disassembly on Leicaplace, was able to get to the inner surfaces with the issues. The glass cleaned up nicely. This is an uncoated lens, 7 elements in 5 groups. After using it on the M Monochrom and M9- I’m impressed. More flare that the Summarit, not quite as sharp wide-open as a contemporary Sonnar. which i also brought along,
Wide-Open, Series VI orange filter in use.
I believe the shape of the aperture of this lens is to minimize focus shift.