Mamiya 7 80mm Lens: Dented Filter Ring, Focus and Rangefinder
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
As you can see from the first photo, this Mamiya 7 80mm lens had a bit of an impact to the front filter ring. In the second photo, I show the result of some body work on the ring. Although a filter will not fit on this ring very well even after straightening (the metal was folded over and the threads damaged with nicks to the ring) it looks a lot better.
This lens had focus and rangefinder issues. Focus did not quite get to infinity on the collimator so even if the rangefinder was working well (which it was not), you would not get the sharp images, especially at wide open, that this lens can provide.
With the lens installed on the Mamiya Multiple Tool, seen in the last photo, it’s obvious that the lens rangefinder cam linear momentum is incorrect. It should be at zero when the lens is set to infinity and it shows 0.10mm. While I don’t have specs on the tolerance for the movement of the cam on the Mamiya 7 lenses, the Mamiya Universal specs are 0.07mm and since the Mamiya 7 rangefinder has tighter tolerance, I would guess that at least 0.04mm would be appropriate. Using the Multiple Tool, I can set the movement of the cam to within .01mm.
After adjusting the lens focus and rangefinder cam, along with the body rangefinder getting adjusted, this outfit is ready to go, just add film.
