Mounting Sinaron W 90mm4.5 DB on Copal#1; Need Help

[Thalmees]

Appreciate any input.
The front cell mount has its thread from inside(see photos please) not as usual(compare it please to the rear cell/pictured), so, it can not be fit directly to the front thread of Copal#1 shutter. Any trick to come around this problem ?
Rear cell has no problem.
Thanks so much.

[JimL]

The male threaded portion is still stuck inside the DB mount. Sinar screwed those suckers in very tightly, so you may have to try a few tricks (solvent, heating, file notches for a spanner wrench) to get it out.

[Thalmees]

Jim, Thanks a lot.
I tried forcefully and carefully to unscrew that ring from the inside diameter, but failed. I even left two dents on the internal side of the ring, not in the light path any way.
This lens is so precious to me; the fastest and really sharp.
Could that ring be found as a separate ring ?
Thanks again Jim.

[Steve Hamley]

Send everything to S.K. Grimes, have them verify the cell spacing in shutter is the same as the DB mount and make you an aperture scale.

Cheers, Steve

[David Karp]

Yup, yours is stuck. It should just screw in the Copal like any set of cells. My 90mm f/4.5 started life in a DB mount, and I had it mounted on a Copal shutter by a local repair shop. They actually just purchased a Copal No. 1 from Nikon, with the scales for a Nikkor 90mm f/4.5, and we did not even have to worry about the aperture scale. Spacing and everything is perfect, it is razor sharp. A beautiful lens.

[JimL]

You may be able to order the part from Rodenstock, but a good repair shop should be able to get the stuck one out...

[Thalmees]

Send everything to S.K. Grimes, have them verify the cell spacing in shutter is the same as the DB mount and make you an aperture scale.
Cheers, Steve
Thanks so much Steve. It could be the only correct move before I damage the aperture blades.
Will contact them for this and for another adapter ring.
Thanks.

[Thalmees]

Yup, yours is stuck. It should just screw in the Copal like any set of cells. My 90mm f/4.5 started life in a DB mount, and I had it mounted on a Copal shutter by a local repair shop. They actually just purchased a Copal No. 1 from Nikon, with the scales for a Nikkor 90mm f/4.5, and we did not even have to worry about the aperture scale. Spacing and everything is perfect, it is razor sharp. A beautiful lens.
Yes, it's a great lens. IC of 236mm on a very well corrected lens at a pleasant focal length.
Compared to Sinaron W 90mm6.8(IC:221mm) in the practice, it looks to me the difference in the IC is not only 15mm, which could reflect that Rodenstock may be more conservative in calculating IC of Sinaron W 90mm4.5.
Could not imagine what a lens like Schneider SA 5.6/90mm XL(IC:259mm), can do.
Appreciate you input David.

[Thalmees]

You may be able to order the part from Rodenstock, but a good repair shop should be able to get the stuck one out...
Appreciate your help Jim. You brought my attention to the correct place.
Thanks again.