Mamiya 7 80mm Lens: Removing a Dented Filter Ring
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
One of the regular tasks that I do here in the shop is removing dents from the front filter rings on lenses. Not an exciting job but often very necessary when work needs to be done on a lens and the name ring needs to be removed as these rings wil not unthread if the lens ring has a dent. Or somtimes, a small dent is preventing a filter from screwing onto the lens.
This particular Mamiya 7 80mm lens took a nice impact that almost folded over the filter ring. Not only was it unattractive, but of course, filters would no longer thread onto the lens.
I use a tool as shown in the photos to remove these dents. Although this was a Mamiya factory repair tool, you can make one of these if you are handy or buy one from @rileys.camera . I’d recommend saving your money and not buying the so called “lens vise repair tool” for straightening filter rings if you want a chance of having a good outcome.
The first photo shows all the tools that I use for this procedure: filter correction stand, punches, ball peen 2oz hammer used for the punches, soft face hammer used for overcorrecting, thread gauge used to clean up threads at 32 TPI.
Second photo shows the lens as it arrived and the third photo shows the stand in use ready for an impact to the top of the punch.
Fouth photo is of the lens with the name ring now removed and visible are the two spanner holes that had been drilled in the name ring sometime in the past as someone probably had an issue removing it. This is something you want to avoid doing (drilling holes) and in the next post I will show how to remove these rings when they are tight without resorting to the brutality of drilling holes.
The video shows the final test: will a filter easily screw into the lens after the repair? In this case, yes.
While I can straighten out most, some dents irrevocably damage the threads and the filter ring is done. In those case, replacement of the filter ring is necessary.
