I just purchased a used Omega D5 XL with an Ilford MG 500 head, and I'm having a problem using both my EL Nikor 50mm f2.8 and my Rodenstock Rodagon 80 mm f4 enlarging lenses with the lens plate that came with the enlarger.
The Nikor will thread into the plate just fine, but seems to stop a bit short of seating all the way down. More troubling is that the back of the lens projects beyond the back of the plate, which means the lens can only be threaded in with the plate already in the enlarger. This seems to be telling me that I've got the wrong lens plate for this lens.
The Rodagon is apparently too big to thread into the lens plate on the D5. This surprised me at first, since I use both lenses with the same 39mm jam nut on my Beseler 23CII. On closer inspection, the Rodagon threads to the jam nut snugly, while the Nikor threads in a bit sloppy, but both would still work in the Beseler enlarger. Sure enough, calipers on the threaded portion of each lens shows the Rodagon is about .005" bigger in diameter than the Nikor. Both these lenses have factory specs that say they each have a 39mm mount, and there are no other measurements given that would suggest that they shouldn't thread into the same opening.
I'd really like to use both these lenses lenses on the D5, as I feel certain that they are far superior to the lenses that came with it (a Fujinon-ES 90mm f4.5, and a Beslar 50mm f3.5) B&H shows a good number of different lens plates available for the D5, but I'k like to know for sure if someone here could tell me which one or ones I really need. If I have to buy these new, I'll pay half again as much for them as I did for the enlarger.
Thanks for any information or suggestions.