El-Nikkor jam nut fit problem

[Moopheus]

I bought a 135mm El-Nikkor enlarging lens to replace the Omegeron lens that came with my D5. I was figuring I could just unscrew the old lens, and screw in the new lens. But the retaining ring that held the Omegeron will not screw all the way down on the Nikkor, so that it is not held tightly on the lens board. There's a good 2mm of space, maybe 4-5 turns of threading. It's a flat lensboard and and a chrome-bodied Nikkor, of that makes a difference. Do I need a different size ring? The two lenses look like they take the same size ring.

[MattKing]

You need a different lens plate far the El-Nikkor.

The Omegaron uses a flat plate - a 421-108.

The El Nikkor requires an extended plate - a 421-932 (or 421-132).

For all (lensboard) things Omega, I recommend KHB's website:

http://www.khbphotografix.com/omega/LensMountD5.htm

[Moopheus]

Cool, thanks for the quick reply. That'll probably end up costing me as much as the lens did!

[bdial]

You might be able to improvise a spacer with something like a plumbing o-ring.

[fschifano]

You might want to try Harry Taylor too. See http://www.classic-enlargers.com/. He's in Stamford, CT, so that might be a better option for you if you're in the US. I've used him to obtain parts for my D4. Very helpful guy. Pleasure doing business with him.

[pschauss]

Another option might be to get a set of M39 macro rings. Several of the FSU sellers on Ebay list them from time to time.

[Moopheus]

The solution turned out to be very simple. Following a tip from Ian C about different ring sizes, I swapped the positions of my 50mm Nikkor and the 135mm. (I have a three-lens turret.) The both fit perfectly this way.