1. Regarding the adapter ring, here's what is on B&H's web site: "When removed, K/L lenses, with the exception of the 75mm shift and 500mm APO, can be used on all RB and RB Pro S cameras." Since this is a RB Pro S body, I removed the ring when I purchased the 127mm lens from KEH. It's included in this lot. I never had rings for either the 90mm or 180mm lenses.

2. For the 90mm lens, the mounting issue is *very* minor; it just takes a touch more force to mount the 90mm lens in the body than it does to mount the 127mm or 180mm lenses because one part of the bayonet mount is out of round. The optics are entirely unaffected by this, and they're perfect.