Mamiya 645 80mm f/1.9: Sand in the Focus Helicoid
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
The 80mm f/1.9 lens for Mamiya 645 came into the shop with a complaint of possible sand damage. The focus ring turned smoothly but every once in a while had a very tiny grinding feel to it. No obvious sand on the externals of the lens.
On disassembly of the lens, there were obvious tiny sand particles visible as seen in photo three. Photo four shows the single bit of material stuck in the focus helix threads that was causing the episodic grinding feel. Of course, all the lubricant was removed and the helix cleaned and re-lubricated. After focus is checked on reassembly the lens is ready to go home.
