EL-Nikkor 150 Thread Conversion & Mounting

[Patrick Thrush]

Some days are better than others... Several months ago I bought an older non-A series EL-Nikkor 150mm (the one with the knurled f-stop ring) on ebay from the camera store mentioned below. I had the mistaken impression that the mounting threads were a standard 50mm. In line with that, I just bought 50mm lensboards for my Beseler MXT and Durst 1200. Imagine my surprise when the lens did not fit in either...

I have since discovered from another thread that this lens was probably intended to use a flange mount adapter, and that the thread size is 53mm OD with a 0.75mm pitch. I could do a number of workarounds for the Beseler including a flange, and epoxy a flange to the Lapla, but the flange does not seem to be available anywhere.

Adorama advertises a Beseler adapter for the turret (BE8374) at $14.95. The claim is that it will take 53mm lens mounts and step them down to a 39mm. My concern is the thread pitch. I can't think of any other lens manufacturer that uses a 53mm configuration other than this Nikon. Has anyone tried this fix, or know whether it would work? I suspect that I am not the first with this question, or hardly the last.

[wfwhitaker]

"Adorama advertises a Beseler adapter for the turret (BE8374) at $14.95. The claim is that it will take 53mm lens mounts and step them down to a 39mm. My concern is the thread pitch."



My concern would be vignetting. Try to find the correct flange or have SK Grimes make you one. It's a nice lens.

[Michael S. Briggs]

Yes, others have had this problem. This version of the 150 El-Nikkor (knurled ring with deep scallops) is a very fine lens, but strongly raises the question "what were they thinking?" when they selected a 53 mm thread. Some previous discussions: http://www.largeformatphotography.info/lfforum/topic/215615.html and http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=003Y4A.





The lens was supplied by Nikon with a mounting flange, so all that the lensboard needed was a through hole and screw holes. The last link above has a suggestion that the part is still available from Nikon (at that time), so you might try calling the Nikon repair center and seeing if the part is still available. At one time Beseler made a lensboard designed to take this flange, but this will be very hard to find now. But adapting other lensboards to take the flange will be fairly easy.





Since the rear element is about 38 mm in diameter, I second the concern that the Beseler adapter to 39 mm might cause vignetting.





Possible solutions: 1) have SK Grimes made a custom lensboard or re-thread an existing Durst lensboard.
This is the option I selected when I switched from a Beseler enlarger to a Durst. When I had this work done several years ago, the price was reasonable. 2) Obtain the mounting flange from Nikon (if still available) and adapt your lensboards to use it, or 3) sell this lens and buy a lens with a more standard thread. The current 150 El-Nikkor has 50 mm thread, and comes with an adapter to 39 mm.

[Robert A. Zeichner]

I had a similar need for my newly acquired Durst 138. I contacted Jens Jensen and he was able to supply a LAPLA 53 with no problem. Fortunately my lens came with a flange and a Beseler board so I was able to use on my 45MXII without a problem.

[Ted Clutter]

I recently purchased on eBay a 150mm el nikkor to which this thread refers. I was bummed out and incredulous that it did not have the modern 39mm threaded throat, but a much larger throat and thread. I followed suggestions here and in other threads, and it appears that you are all wrong! I bought a new old stock Beseler turret adapter, 53mm to 39mm, at Adorma for $23.50 delivered, and found that the threads on this lens are larger than 53mm.... which now looks more like 55mm (no, I could not even get the lens started in the thread, so it is not simply a different pitch). My temporary solution: I filing out a 39mm Beseler board to fit the lens, then unscrewed its front cosmetic ring, which serves as a workable retaining ring on the back threads of the lens. It works fine. However, I would rather that this ring be in its rightful place on the front of the lens. I just bought a cheap 58mm to 55mm step down ring on eBay, taking the chance it might work as a retaining ring. Why in hell would Nikon make this absolutely stupid choice when designing what appears to be in all other respects a fine piece?

[Tom Westbrook]

The Schneider APO Companon 150mm f/4 (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=46279&is=REG&addedTroughType=categoryNavigation) has a 55mm mounting thread size. Beseler has/had a special lens board (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=4527&is=REG&addedTroughType=categoryNavigation) for it that you might be able to find (it has an inch or two of extension built in, too). You need a jam nut for it. I had to do a bit of scrounging for a 55mm board for my LPL 4x5 enlarger and found one by calling a few suppliers.