Disassembling Elmar 90mm (9cm) F4

[kens-o]

Hi,

I bought a M-mount Elmar 90mm F4 lens. The lens has a trouble in apertures. So, I tried disassemble the lens to fix the trouble. I found this page about the disassembling of the lens.
https://www.photrio.com/forum/threads/loose-aperture-blades-on-leica-elmar-90mm.118879/
I followed it. However, I noticed my lens is little bit different from one in the above page. I could unscrew the top plate and remove first lens element. This is the disassembled lens.

But I could not go to next. Any parts could not be disassembled. Then, I tried disassembling from bottom side. I could unscrew the bottom lens element, but then I could not go next. This is the bottom side.


How can I reach the aperture blades? The lens barrel is seemed one piece. Anyone success disassembling the lens?

 

[John Koehrer]

It looks like the black ring in the pic is threaded, Standard right hand thread.
A rubber stopper that fits inside the barrel and possibly a drop of penetrating oil on the threads may do it.
Use the penetrating oil ONLY AFTER trying to unscrew it dry.

Replacing the blades is a pretty delicate task so I've used a film can inserted from the back
can help hold them in position while you work.

 

[kens-o]

Thank you for your reply!
I tried to unscrew the black ring, but I could not open it...
I carefully watched the barrel, and I thought the silver one and black one cannot be detachable.
How do you think? The screw hole seems to be connected from black one to silver one.

 

[shutterfinger]

Try soaking the threads between the black (inner) ring and the silver (outer) ring with Acetone for 5 to 15 minutes then try to unscrew the inner ring again.