Thomas, the old 150 EL-Nikkor with the 53mm thread uses a flange instead of a locking ring. If you get an old timer at Nikon parts you can get the correct flange. By the way, I use mine for 5x7, something the newer ones won't do.
Yeah, my lens doesn't have the ring, so something else must be worked out. I'll look around to see what I can find. Thanks for the info regarding 5x7. That's good to know if I ever get an enlarger for the full format.
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