Mamiya 7 65mm Lens: Loose Filter Ring Screws
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
A common issue with the Mamiya 7 lenses is that the filter ring screws become loose. The video shows how this 65mm lens arrived with the front ring loose and fortunately this problem was addressed before one or more of the screws became totally loose and caused deeper issues. Also, the ball bearing and tiny spring that provide the detent can come loose and that is not good.
The third photo shows the three screws that get loose. To access these, the name ring, front element group and diaphragm coupler need to be removed. I reinstall the screws using low strength purple threadlocker so that it will not vibrate out yet can be removed when/if the lens needs disassembly in the future. It seems like I find these screws either extremely tight from the factory or loose, not much in between.
The final photo shows the shim used on this lens for calibration and it is a 0.3mm. There are three sizes that Mamiya used: 0.3, 0.1, 0.05 and these are used to match the front and rear element groups.
