Disassembling a Xenotar

[Paul Ewins]

There has been a flood of ex-government Xenotars on eBay lately, mostly the 150/2.8, and mostly in a strange sort of barrel mount. I took a chance and bought one and am having an, umm, *challenging* time getting it apart. The front cell came out relatively easily but I can't for the life of me get the rear cell out. It seems that lurking inside some rather large pieces of aluminium tubing is the original Schneider barrel mount, but the rear cell is tightly held by the tube and I can't get much purchase to try and unscrew it. There isn't anything visible to give me a clue how it is held in place and I fear that there may be glue involved.

Has anybody else bought one of them and been able to disassemble it successfully? The front cell screws straight into a compur 2 5/2 as expected so once I get the rear cell free it is a straight fit into a shutter.

[John Schneider]

Shine a bright light in the back side and see what you've got. In the one I bought, the rear cell had two notches cut into the barrel. The ID of the custom mount was just barely larger than the OD of the rear element, so I spread my SK Grimes spanner so that it scraped the ID on the custom mount (so that a slip wouldn't result in a scratched element).

Because the cell was in there so tightly, I carefully sprayed some penetrating oil on the threads from the front side (after removing the front element and opening the iris). For greater control I clamped the spanner, points up, in a vise and carefully (and with lots of effort) turned the custom mount to unscrew it from the lens cell. I didnt have to use a strap wrench so it wasn't on *too* tightly.

I had two 150s and a 135 pass through my hands, every one in a different Photo-Sonics mount for a high-speed camera. Just take your time and you'll figure things out. Be aware that there may be setscrews locking some threaded elements. And every one had haze between the lens groups in the front cell, necessitating unscrewing the front retaining ring, removing the front lens, and cleaning things with xylene and filtered compressed air.
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As an aside, does anyone know if there was a particular timeframe when these 150s were threaded to fit in a Copal 3, or if it was done on a batch basis (and if so, the s/n range)? The one I bought was in the 12,2xx,xxx s/n range, and after all this disassembly turned out to be threaded for a Compur 2, unfortunately. This s/n was much later than the super-nice 150 that Jim Galli sold here a while ago (s/n in the 7,xxx,xxx range as I recall), which was factory-threaded for a Copal 3.

[Paul Ewins]

Mine is 12,696,xxx which makes it 1974. Some of my Symmars have adapters to make them fit a Copal 3 rather than the cells being redesigned to fit. I would guess that any existing design got the adapters when the Compounds and Compurs became unavailable rather than being redesigned to fit a Copal 3.

[Jason Greenberg Motamedi]

I have a very late model 150/2.8 Xenotar--serial number around 14,000,000--which was factory fit into a Copal 3. However, like all the other 150/2.8 Xenotars I have seen the barrel has a thread for a number 2, and has adapters to fit into the number 3 shutter, so I think you are right Paul.

[John Schneider]

Jason, when you have a chance would you mind posting some digi pics of your adapters, and maybe a few basic dimensions? It would be a help in getting adapters made locally (SK Grimes is great but expensive, as everyone well knows).

[Jason Greenberg Motamedi]

John,

A much easier route is to buy a convertible 240/5.6 Symmar in a copal 3 and pull the adapters off them. Or, buying a 240/5.6 Symmar in a Compur 2 and just using that shutter. I will try to see what I can do about the images this week.

jason

[Paul Ewins]

It turned out to be a bit more of a struggle but I prevailed in the end. The rear cell was very tight so I had to cut the back of the barrel off, about 6mm or 1/4" form the threads. It slipped right off and I could then get a grip on the rear cell. Even with penetrating oil I had to resort to a couple of strap wrenchs (actually cheap oil filter wrenchs with some strip rubber to provide grip and protect the finish) before it would come apart.

Theoretically a 270/5.5 Tele-Xenar should be another candidate for a shutter swap, but it may depend on the age of the shutter. I've got a 1950 Tele-Xenar in a dial set compur 2, but the Xenotar front cell won't screw in all the way as it is slightly longer than the Tele-Xenar.

[Daniel Unkefer]

I'm bidding on one right now, I want to mount it (in the original Schneider barrel mount) onto a flat Plaubel Makiflex lensboard. It's one of the factory-original lenses offered for the Makiflex, which I have two of. Should be wonderful on 4x4 inch sheet film!

[Paul Ewins]

Good luck with that Daniel, although there seems to be no end to these lenses at the moment. Prices seem to have settled a bit to be reliably in the high $200s (mine was just shy of $300) so it seems to be just a matter of patience rather than a feeding frenzy. I doubt that any of them will be pristine, but I would regard mine as a "user" rather than a "junker".

Mine eventually went into a Compur 3 that I got for a pittance because the shutter was faulty. When I took the cells out it started working properly so it may just have been overtightened somehow. Originally it was a 240/420 Symmar with adapters to match the new thread size. FWIW it seems that the approximate changeover time from Compur 2 and Compound 4 to Copal/Compur 3 is 1970. At this point the 355/6.8 Symmar in a size 3 shutter appears in the catalog alongside the 360/5.6 Symmar in an Compur-Electronic 5FS and both the 240 & 300 are shown as mounted in size 3 shutters . By 1972 the Symmar-S had been introduced with everything redesigned to suit the 0,1 & 3 sizes.

[Daniel Unkefer]

Hi Paul,

Yes, I did win the 150mm F2.8 Xenotar from Labgeartrader, and yes, I got mine for $271, and it appears in better condition than alot of the other ones I've seen listed. Mine will stay in the barrel mount, since I'm mounting it on a large-format camera with focal-plane shutter. It's presently mounted on a relatively thick flat circular metal plate, so removing it should be straightforward. It even has the original lens mounting flange, which I will need to remount to my metal Plaubel Makiflex lensboard. This seems to be a relatively expensive lens, sometimes offered at over $1000, although I had a chance to buy one at a camera show ten years ago for $200, but I didn't like the condition on that one.

If the glass is "milky" between the elements in the front cell, I will probably try cleaning it myself, although I could send it to John Van Stelton at Focal Camera Repair in Colorado. I think it would be fun to do it myself.

How difficult is it to remove the lens front ring and clean the elements? So I'm happy and just waiting for my new lens, so that I can begin this new "project". I'm especially interested in original lenses offered for the Makiflex, I do have the original Plaubel literature on these cameras.

Where's a good place to buy "Xylene"?

[cdholden]

I've seen Xylene in Home Depot.
It's similar to benzene, so protective gloves and a respirator mask work in your favor.

[Daniel Unkefer]

I've seen Xylene in Home Depot.
It's similar to benzene, so protective gloves and a respirator mask work in your favor.

Thanks for that! Will try our local Home Depot.
I googled around, and Sherman Williams paint shops seem to sell it.
But ten gallons is more than I need!

[John Schneider]

The extra two methyl groups make xylene a lot safer than benzene, but gloves and a respirator are still recommended. Just realize that a dust mask won't help at all (not to talk down to you, but I've seen postdocs do it) and xylene goes right through nitrile and latex gloves. Thick chemistry "acid" gloves and the like are fine.

Most paint stores and paint departments of places like Lowe's and Ace sell xylene in pint cans. Also, xylene is used in many auto paints, so an auto paint store would certainly carry it.

[Daniel Unkefer]

It arrived today, and overall, I'm pleased. It has two smaller dents, and one big one in the front ring. The back cell also has a big ring dent, and a small peck in the center of the glass. The front element has alot of fine scratches, but nothing I think will affect performance. The lens came off the mounting plate in two minutes, and has the original flange, I'm glad about that. The iris is real tight to turn, it needs a clean. No milky haze that I can see, just alot of fine scratches.

I will send the lens to John Van Stelton at Focal Point Camera Repair in Colorado, he has redone a number of alsorts of lenses for me, and does fabulous work, including resurfacing front elements (he did my badly scoured 50mm F2 Leitz Summicron and it's now like-new). He can also straighten the problems in the front ring, he's done it for me many times.

Here is what I got:

[Daniel Unkefer]

OK I talked on the phone with John Van Stelton at Focal Point today. He was frankly not too impressed with my Xenotar, would not recommend putting alot of money into recoating it. I mentioned to him that I had looked through it, and it seemed OK to me. He said for $125 he can straighten out the front ring as best possible, to get a filter on. And strip and clean the aperture mechanism, that's in pretty bad shape. He said he will also pull all the elements and clean them, he thinks there's some crap in between some of those. Not really something I want to do myself.

I'm sure I'll be pleased with what I end up with. Anybody else shooting anything yet with these Xenotars?

I saw Igor from Cleveland last weekend, he told me he has an automatic version of the 150mm Xenotar, for the Makiflex Automatic. But the lens has a very bad scratch across the lens front, so he needs a good front and back cell to put his into order. I will be using this lens on both of my Makiflexes, the Standard, and the Automatic.

[salihonba]

screws are hidden in the iris tube (or focus tube?) to fix the rear part, take off the outer rim then you can see those screws, three or four I don't remember.......

[Daniel Unkefer]

I called John at Focalpoint today, and he just shipped out today my 150mm F2.8 Xenotar. He removed the dents from the front ring (so I can attach a Skylight filter and rubber lenshood), removed the milky deposits between the elements, and completely did a CLA on the aperture mechanism. And I couldn't get the flange to budge off the mount. I'm sure it's as good now as it can possibly be, and I can't wait to shoot with it on my Plaubel Makiflex body. Not bad price at all, $125 for all that work. Especially the collimation part. I'll post a picture when it's all completed and usuable, still have to enlarge the lensboard hole and mount the big Xenotar. Quite kewl.

[Daniel Unkefer]

My 150mm F2.8 Xenotar arrived yesterday, and I wasted no time getting it mounted onto a Plaubel Peco Junior board. Took about an hour using a metal file to adjust the board hole size. Attached it with small machine screws, so now I'm finally ready to look through it.

I have used this flat board with a 150mm Symmar previously, and it focused to infinity on my Makiflex. But with this lens, it appears that I will need a recessed board if I need infinity focus. Either that, or the lens cells are not lined up correctly?

It focuses, and I see detail on the groundglass, but Man, is the DOF thin! I will use it as-is for a while, for closer up shooting. I can focus out to about fifteen feet at most. I'll have to find a recessed Peco Junior board, if this is normal for this lens.

I have a 150mm F4.5 Xenar coming, so I will be able to make a direct comparison. I think I like it so far!

[Daniel Unkefer]

OK my Schneider Xenotar 150mm F2.8 project is -finally- finished. I had to mount the lens on a Plaubel Peco Jr recessed board, to get infinity focus with my Plaubel Makiflex Standard. This is one of the original lenses for the Makiflex (back in the 1960's) so I am really pleased. Focuses great and the groundglass image looks really good. I can shoot film and plates from 6x6cm to 3.5"x3.5". I know I will be using the Xenotar quite a bit on this outfit.

Really glad I was able to get this lens for a reasonable price from Labgeartrader.