This little, well-built Chinon 55mm f/1.7 Auto lens is a fantastic lens stopped down a bit. It is a little soft wide open but makes a good low light lens with an adaptable M42 mount.
This Chinon 55mm f/1.4 Auto is fantastic mechanically and optically. There is not a whole lot of talk about this lens and probably for one reason. The rear element sticks out a fair bit and can hit the mirror on certain cameras if your using it on a DSLR with an adapter. However moving the focus away from infinity makes enough room to shoot or with the mirror up.
I feel bad for the people who bought their nice new Ricoh camera with this Ricoh Riconar 55mm f/2.2 kitted with it. This lens is very poor. However if you want some strange and artsy spherical aberration, this lens is interesting to play with.