Mamiya SF 150mm RB Lens: Drilled Name Ring and Parts Donor
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This Mamiya SF 150mm RB lens came to me with a name ring pre-drilled and a filter ring with some subtle dents. These are not too important flaws in this case because this is going to be a parts lens as the glass is damaged beyond repair. The lens will live on as it gives up a nice 791 shutter for future lenses in need.
A bit irritating that someone felt the need to drill spanner holes in the name ring in order to remove it. Really, all it takes is the correct tool and although I have the factory (very soft) rubber removers, a solution can be improvised other than a drill bit!
Speaking of RB shutters, there were three styles for the various lenses: 30mm, 25mm or 20mm opening. The correct shutter depended on the lens design, not the maximum aperture or focal length of the lens. Photo four shows the three styles with the 30mm in upper left (white retaining ring), 25mm in upper right (yellow retaining ring) and 20mm on the bottom (black retaining ring).
As a comparison, the RZ used thirteen different shutters on its lenses. I won’t be showing all those variations.
