Mamiya 645 80mm f/1.9 N: Wrong Lubricant on Focus Helicoid
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This Mamiya 645 lens, 80mm f/1.9 N, came into the shop with a focus that was very tight and grinding. Seemed to have no lubrication on the focus helical. On disassembly, the threads were found to have a moly type of lubricant on them (photo three shows the grey lubricant on a tissue that I wiped the threads with). They should have a focus helicoid lubricant on them (typically lithium and PTFE) which gives the threads a smooth movement. My guess is that this lens had a very light lubricant installed because it was used for cinema work?
This particular example is from the first batch of production in 1986.
As you can see in the first photo, there is an Amazon Basics UV filter on the front of the lens. This was my first chance to test these filters and it does not measure too bad- the front and rear surfaces are one minute out of parallel. For a 67mm filter, this is probably within specs. Although high quality filters like B+W can be closer in parallelism. In general, I am not a fan of UV filters!
