Nikon 55mm f 1.2

Nikon 55mm f1.2

Problem: Fungus

The Nikon 55mm 1.2 and its two sisters the 50mm f1.2 and the 58mm f1.2 are the two fastest lenses for SLR by Nikon ever made. The Ai-S version of the 55mm is still sold new and there is no autofocus lens as fast for the Nikon system (for Canon there is the  perfect 50 F1.2L)

I actually got two similar lenses one from 1967 and one from 1971-72 (based on serial numbers). Both had few fungus stops on elements around the aperture.

This is actually quite an easy fix. The lens can be taken apart into two main assemblies: the focusing assembly and the optical one.

Fig 1 - The spot of fungus can be seen under "Nippon"

We start by removing the front ring. First you need to unscrew the small set screw in the side of the ring and than simply undo the ring (is stuck two tight, you can use the small screw as a lever and turn with a spanner - or something)

Fig 2 - The small set screw, just under the letter N in Nikkor-s

Ones the front ring is removed, you can simply take out the whole optical assembly. This is the time to point our that if you only want to get to the glass inside, or the front of the aperture, you don't need to take the whole thing out.

Fig 3 - Optical assembly is out.

Next the front element group can be unscrewed using a spanner and using it on the two grooves at the front of the lens. Having done this, one can clean the inner elements, As always, I use a Q-tip with some white vinegar on it to remove and kill the fungus. Next I use another Q-tip and clean the residue with some IPA and finally cleaning everything dry with some lens tissue or a cotton ball. 

Fig 4 - Clean.

The assembly is actually tricker if you need to put back the optics. You should align three things, the aperture lever, the auto (spring) lever and the slot and screw (screw on the side at the front of the opics). I found its easier to do with the stepped down, set the aperture ring to F16 and slowly get it in there - It will take few tries, and cries, but you'll get it in the end.