This is an uncommon lens, not too many outside of Japan. This one is from an Ebay seller in Japan, bought it about 5 years ago. It is an Ultron formula lens, 6 elements in 5 groups. A variation of the Double Gauss. Minolta used this formula for years, including the 45mm F1.7 Minolta-PF in my Minolta Hi-Matic 9 that I bought in 1969.
Current prices on Ebay range from ~$250 for a good looking lens with some coating marks to over $500.
This is a relatively large lens for an F1.8, uses 46mm filters and hoods. It is about the same size as the Zeiss C-Sonnar. The Canon 50mm F1.8 v2 (Black) lens in LTM uses 40mm filters and hoods.
This lens is well balanced on a Leica M.


I noted the lens close-focuses as F1.8, and has some focus shift. It is optimized for F2.8 or so. It would be perfect wide-open on my M Monochrom with an Orange filter. I'll have to try that.
F1.8 and F4.


F1.8 and F2.8 Pair.


The focus shift is only noticeable at 100% pixel peeping.
The aperture is shaped like that of the post-war Zeiss 50/1.5 Sonnar, a design used to mitigate focus shift.
Current prices on Ebay range from ~$250 for a good looking lens with some coating marks to over $500.
This is a relatively large lens for an F1.8, uses 46mm filters and hoods. It is about the same size as the Zeiss C-Sonnar. The Canon 50mm F1.8 v2 (Black) lens in LTM uses 40mm filters and hoods.
This lens is well balanced on a Leica M.


I noted the lens close-focuses as F1.8, and has some focus shift. It is optimized for F2.8 or so. It would be perfect wide-open on my M Monochrom with an Orange filter. I'll have to try that.
F1.8 and F4.


F1.8 and F2.8 Pair.


The focus shift is only noticeable at 100% pixel peeping.
The aperture is shaped like that of the post-war Zeiss 50/1.5 Sonnar, a design used to mitigate focus shift.