I got a hold of a Leitz 5cm f/2 Summicron-M collapsible lens … one that was in really bad condition, which was the only way I could afford grabbing this type of lens. I have to say (and I knew for a long time) Leica M stuff is EXPENSIVE (I thought the LTM was over priced).
I did not do a complete dissasembly … like getting at the focus helicoid.
The lens is actually not that difficult to work on, but just requires a bit of pre-info … since you really don’t want to damage a Leitz.
The front element is very soft so it is noted on being very easy to scratch when cleaning. This one has heavy haze and fungus.
To get to the aperture blades you can just unscrew the entire front group off.
Getting between the elements of this front group is something I did not even attempt to do.
You can remove the rear cap section, but you have to do one thing first. There is a small screw in the side of the lens barrel, loosen that first
It is a brass screw, so watch out !!!
before using your spanner wrench to unscrew the rear retaining ring.
The collapsible lens rides on two slots, and the rear focus ring has two bearings inside it … so try not to loose them … and when putting it back together you have to line up the slots.
You can see the two bearings (the left one is missing in this shot).
Here is a picture of the end cap attached to show how the slot should line up.
The encap goes on after placing the focus ring on … so you will have to eye ball it.
Then screw the retaining ring back on with the spanner wrench without turning the end cap … then secure the side screw.
This Old Camera 