Mamiya 645 80mm f/2.8: Over-Lubricated Focus Helix and Diaphragm
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This 80mm f/2.8 Mamiya 645 lens came into the shop with complaints of stiff and uneven focus and sticking diaphragm blades. On disassembly, I found that the focus helix had been lubricate with a large quantity of moly lube. Worse yet, the diaphragm assembly also had quite a bit of oil mixed with moly lube and this was causing sticking issues. Photo two shows the layer of lube on the top of the focus helix threads and photo three is a close up of the focus helix showing the large amount of lubrication in place.
I certainly don’t expect most technicians to have the factory recommended focus helix lubrication for this lens (Kahata 3D/002), but there are plenty of lubricants that would work fine. And coating the moving parts of the diaphragm operating system with lubrication is very wrong!
