Retaining ring stuck. Carl Zeiss Jena 20mm f2.8

WM1 · Joined: 14 Oct 2023 Posts: 17 Location: United Kingdom

Tried the rubber tool. Used isopropyl alcohol and acetone to try and release it to no avail. The nameplate and retaining ring are severely stuck it seems.

DConvert · Joined: 12 Jun 2010 Posts: 921 Location: Essex UK

Localised heating with something like a soldering iron MIGHT help.

As a last resort you could drill two holes in the name ring so as to enable a lens wrench to grip on it. Not something I'd like to do on such a nice lens - but if nothing else works it might give you a way forward.

RokkorDoctor · Expire: 2025-05-01

Hard to tell from the image but If you do manage to loosen the lens retainer ring, you may find as you unscrew it it is still stuck behind the name ring.

On 20mm~ish wide-angles like that often the name ring & filter holder are one machined unit that needs to come off before the front lend group (or front element retainer ring) can be removed, especially if they are of the type where the filter thread rotates when focusing. Screws and/or fixing tape that allow the name ring and filter holder to come off are sometimes found underneath the focus grip waffle.

If that is the case with this lens you may also find that once the front group is exposed, you see thread-lock holding the front element retainer ring on an external thread rather than internal thread (i.e. the retainer ring may have a female thread and the cell body a male thread). This isn't always obvious from the outside.

WM1 · Joined: 14 Oct 2023 Posts: 17 Location: United Kingdom

For posterity, I used a small amount of 3 in 1 oil and let it work for a couple days and I was then able to remove the retaining ring. Nameplate didn't need to be removed to access the lens elements.