jam-nut size questions(EL-NIKKORS)

DanielStone · Nov 11, 2010

hey all,

I'm currently watching a 210mm el-nikkor on the 'bay, for my 4x5 negs, but it doesn't have a retaining ring(jam nut) included with it.

also, I just received a 63mm (3.5, NOT 2.8) el-nikkor in the mail, and it doesn't have one either, so I'll need one for it too.

planning on making some masonite lensboards anyhow .

any ideas of where I can get one for EACH, and how much they would cost?

thanks

-Dan

ann · Nov 11, 2010

I would think b&h and freestyle would have them, think at least 10-15 dollars.

Jim Jones · Nov 11, 2010

I've also used Leica Thread Mount flanges and extension tubes for jam nuts on enlarging lenses.

Dan Henderson · Nov 12, 2010

Isn't 210mm kind of long for enlarging 4x5 negatives?

Ian Grant · Nov 12, 2010

As Dan says you'll struggle using a 210mm for 5x4, it'll hamper making decent sized enlargements.

A 135mm Copmonon/Componon S is designed for 5x4 and is a very practical focal length for a bench enlarger, if your enlarger is floor standing then q 150mm is a good choice as well.

Ian

David Brown · Nov 12, 2010

The 63mm Nikkor should be a 39mm (leica) thread. The jam nuts are common enough. I agree with the others that you should be looking for a 135-150 for your 4x5 negs.

dentkimterry · Nov 12, 2010

The 210mm EL-Nikkor takes a 72mm retaining ring. The 63mm f2.8 takes a 39mm ring. Don't know about the f3.5. Not sure where you can get one. Maybe Nikon parts has one.

Terry

Mike Wilde · Nov 12, 2010

I have DIY'ed a square plate aluminum lens board and fimo modelling clay jamb nut when I owned a Beselar 23 and was shy on a board for a rarely used lens to cover 6x9, since I principally shot 6x6.

I put the lens though the hole in the board (mine had a hole that was a tad oversized), and rolled the Fimo into a long round ribbon that I wrapped around the protruding threads and pressed into place. I left it to dry for a few days, and then trimmed excess that had been 'extruded' on the far side with a sharp knife. I took a Sharpie black marker to the dried clay , and that was that. We were good to go.

Smudger · Nov 12, 2010

Just to add to Mike Wilde's post,I did something similar with a 150 EL-Nikkor,which has an exotic and hard to obtain jamb nut.
I used epoxy putty,and greased the thread on the lens with petroleum jelly before assembly.
The lens can be unscrewed if required.

ic-racer · Nov 12, 2010

SK Grimes will make what you need if you can't find one. Look around first. Mike123 had a bunch of flanges (I got a 75mm from him) and rings but he is gone now.

MartinP · Nov 13, 2010

Isn't the 39mm thread a standard metric one ? Any metal shop can put a hole is some steel and thread it for you, though it would be more convenient (and probably cheaper) to find one ready made. The idea of packing epoxy round a greased thread can work too - I have tried that succesfully for ventilation system parts with good results.

ic-racer · Nov 13, 2010

MartinP said:
I Any metal shop can put a hole is some steel and thread it for you, though it would be more convenient (and probably cheaper) to find one ready made. The idea of packing epoxy round a greased thread can work too - I have tried that succesfully for ventilation system parts with good results.

Yes, any shop that is making 39mm Whitworth threads So, on this continent that would probably be SK Grimes....

Jim Jones · Nov 13, 2010

MartinP said:
Isn't the 39mm thread a standard metric one ? . . .

The LTM is 39mm in diameter, but a 26TPI Whitworth thread See http://en.wikipedia.org/wiki/M39_lens_mount for one explanation.

Bob-D659 · Nov 13, 2010

A 39x1 mm ring will jam.

MartinP · Nov 13, 2010

Jim Jones said:
The LTM is 39mm in diameter, but a 26TPI Whitworth thread See http://en.wikipedia.org/wiki/M39_lens_mount for one explanation.

Ooooo, it seems that the Leica thread is indeed not a Metric one. I vaguely recall reading about the FSU pre-war thread vs. Leica difference, but didn't appreciate the reason.

Strangely the Wiki article is a bit wrong too, or at least misleading. The Leica thread seems to be British Standard Fine (BSF), which is one of the Whitworth family but not the 'standard' thread pattern. The normal Whitworth thread is very robust (a relatively heavy coarse pitch/profile) and can withstand a lot of corrosion before jamming unuseably.

Quarter-inch Whitworth bolts used to be used for all sorts of garden and farm tasks in UK. I'm English (though I don't live there anymore) and recall when the vendors started selling 6mm Metric bolts to replace the 1/4" W it was quickly found that Metric Coarse was a better match for the functionality of the Whitworth design, though arguably not quite as robust.

You could say that the standard Whitworth thread was more like Metric Coarse, while the standard Metric thread was somewhat similar in design to B.S.F. It stretches my memory a bit, but I think I recall that there was a very fine instrumentation-purposes thread as well. Luckily Leica didn't borrow that one, else we'd never get an over-tightened lens off - clearly they knew what they were doing!

John Koehrer · Nov 15, 2010

nut(s)

pm your address & I'll throw a Leica/Nikon/Minolta 39mm nut in the mail for you.
Postage should run about a buck.

jam-nut size questions(EL-NIKKORS)

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