Removing a 75mm f/6.8 Rodenstock from its lens board

I am trying to remove this lens from a Sinar lens board and mount it on a Linhof lens board for use on my Technika V. If anyone has any insight to my issue, I'd very much appreciate some advice.

The rear section of the lens is quite easy to unscrew and remove, but it leaves me with a black ring that I think should also unscrew. For the life of me I cannot get that ring to unscrew so I can access the actual retaining ring mounting the lens to the lens board.

Anyone know if I am missing anything and if not, have any insights into how to remove that section of the lens w/o damaging anything?

(I can't seem to upload any images, regardless of their size -- they all come up as "too large".)

Many thanks for the help!

Are you using a proper lens wrench/spanner?

It won't be easy to get enough appropriate torque without one and you don't want to mess up and damage the lens inadvertently with something make shift.

Without a photo, most of us don’t know what other ring might be preventing you from getting to the retaining ring.

Once you get it off, the following is easily done with a proper retaining ring wrench.

A one-piece shutter-retaining-ring wrench is the safest tool to use. The Toyo wrench covers #0 and #1 shutters.

https://www.bhphotovideo.com/c/product/61131-REG/Toyo_View_180_625_Lens_Mounting_Wrench.html


The Rodenstock wrench and the Catlabs copy of the Rodenstock wrench work with #0, #1, and #3 shutters.

https://www.bhphotovideo.com/c/product/1605177-REG/catlabs_clws_lens_wrench.html

https://www.bhphotovideo.com/c/product/131992-USA/Rodenstock_260600_Metal_Lens_Wrench.html

You must use the correct end for the particular shutter. They're well-marked. The key to safe ring removal/tightening is to press the tool inward towards the ring with greater force than the torque you apply to turn the ring so that the tool doesn’t slip out of the dive grooves in the ring and damage the ring or the shutter.

Thanks, guys. I need to get a photo uploaded. I do have the Rodenstock wrench -- let me work on uploading a photo. I don't think I can make any progress w/o showing you what I'm looking at.

OK...got the photos uploaded. The first image is obvious -- the rear of the lens is attached, normal config. In the second, the rear of the lens is unscrewed and detached showing the retaining ring underneath the larger diameter ring above it. Blue arrow points the recalcitrant larger diameter ring. I assume the larger diameter ring unscrews so one can access the retaining ring? It's the larger diameter ring that is giving me fits...

As I think you can tell, the Rodenstock wrench doesn't extend far enough down to reach the cut outs in the retaining ring. That fact is what makes me think the larger diameter ring must be removed next...

It appears that you left a piece of your rear lens assembly attached to the shutter, and from your account, it is stuck on good. I had a similar situation, I was even able to loosen the retaining ring but could not safely apply sufficient turning torque to the shutter housing/front cell combo to remove the rear cell. You could get lucky and unstick it if there is only light corrosion holding you up; in my case, the prior owner used threadlocking compound, so it was no go. SK Grimes charged me plenty, even including fabricating a special tool that I paid for but was not allowed to see, and they got it apart. It still cost a lot less than a replacement lens would have cost me.

Try wrapping a rubber band tightly around the stubborn ring for more grip when trying to remove the ring.

Try also a filter wrench, or something like this:

Many thanks everyone. The previous owner really screwed that thing down. It would not give no matter what I did or what tool I used. Finally, I very, very judiciously applied a little heat, then (also very judiciously) a little WD40 to the threads, then used a multi-sized jar opener I had tucked away for just such an emergency. It then came right off.

EHM2, thanks for the conformation that what I was dealing with was an actual part of the lens assembly.