Cleaning the glass on a 90/4 LTM Elmar

[KoNickon]

I have seen several threads from this forum and elsewhere about how to get at interior lens surfaces on this lens, but they don't appear to be exactly the version I have.

Mine is the four element, with black name ring, 1247xxx. The name ring has a couple of holes for a pin spanner, but on closer inspection it looks as though in fact those are holes for set screws (?). I tried loosening them but the name ring didn't budge. Is it necessary to even unscrew the name ring? It appears as though the haze is on the front two elements, so presumably I'd want to get the front element out and clean its back surface, and the front surface of the second element, at the very least.

So in short, any guidance on how to proceed would be most welcome. Thanks.

 

[charjohncarter]

I don't see a grub or regular screw within the name ring holes of my 90mm Elmar.

 

[Phil_F_NM]

There are a few different versions of this lens within the 4 element, 3 group batch, not counting the 3 element version.
I've owned a later version with only a beauty ring that has spanner notches, not holes. Just looking online at different versions of the 4 element 9cm/90mm Elmar, there appear to be at least 4 different presentations of the front side of this lens, all with different beauty rings.

All that said, you may be able to get to yours from behind by removing the rear groups and doing your cleaning through the aperture. If you have a version which unscrews from the focusing helicoid for Visoflex use, this approach should be the least invasive and easiest to perform.

Phil Forrest

 

[KoNickon]

Hmm, good suggestion. Yes, this version has a removable optical assembly for Visoflex use. I see a collar around the rear group with spanner notches. It won't let me get at the back of the front element or front of the second element, though, which is where I think much of the haze is located.

 

[analoged]

The front element just unscrews from aperture ring; if it's stuck throw the whole optical unit in the freezer for a bit!

 

[KoNickon]

Can you be more specific? What am I supposed to unscrew? There's a winder flange just in front of the aperture ring; is that what unscrews?

 

[Phil_F_NM]

Be careful when applying force to any aperture ring. If the aperture ring is the only thing to grasp, the tabs on the blades will shear off far sooner than the threads will break loose. Also, you need to ensure that yours is a version which comes apart this way.

Phil Forrest