Mamiya 7 43mm N Lens: Removing the Rear Element and Name Ring
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
Servicing a Mamiya 7 43mm N lens.
The 43mm has a different build than the 80mm and 65mm especially in the rangefinder mechanism. This is because of the very large rear lens element. When removing the rear element, I use a purpose made lens removing tool as the notches for the spanner tool are very close to the rear cowl and also to the large rear glass element. The third photo shows the tool inserted in the cowl to remove the rear element group and as you can see, there is very little tolerance between the tool and the cowl.
Also, the front name ring on these often does not want to unscrew at times (even with the correct size rubber tool) as it is thin plastic and easily binds in the front filter threads. Especially if the threads have any kind of damage to them, however slight. My technique for getting the rings off easily is to use what is shown in photo four, Dupont Teflon Dry Film Lubricant. This is basically PTFE in a Heptane and Isopropyl alcohol base. A small amount is drizzled onto the threads, the liquid soon evaporates and the PTFE remains to lubricate the threads and ease removal of the name ring.
