Xenotar 150 - Safe to mismatch cells?

[tbeaman]

I think everyone is familiar with the glut of these surplus lenses that have been sold within the last while. I received mine not too long ago with some shipping damage. The front filter ring was banged up, and it took quite a bit of effort to get it out of the weirdo housing, after which I discovered the front cell had been knocked so hard it was cross-threaded within the barrel mount.

The seller has been gracious enough to offer an exchange, either for the whole thing or just the front cell and mount. My question is, should I keep the rear cell, or send the whole thing back? The only reason this isn't an obvious choice is that the condition of these lenses are somewhat dubious and unpredictable, and this one's rear cell is immaculate. The front cell has a starry night sky full of nicks, but that was acceptable to me. The important part was the rear was clean, and the front at least had no coating damage or smudges, and neither had haze.

From another similar thread, I take it that Schneider doesn't recommend mismatching cells from the older lenses, because the manufacturing process didn't guarantee good matches unless tested. On the other hand, it was said that it may be safe with symmetrical designs like the Symmars and other plasmats. Does the Xenotar count amongst those that would be safe?

I suppose if there's any chance the cells won't match well, I'll just send the whole thing back. I think I'm just looking for confirmation through raise of hands.

[Jason Greenberg Motamedi]

Send the whole thing back. The 150/2.8 Xenotar has gone through at least one major redesign, if not multiple tweaks along the way.

[tbeaman]

Well, one reply is better than nothing. Thanks, Jason.

I hadn't even considered the possibility of design changes. I'll send back the whole thing.

[Frank Petronio]

It seems like a lens like that, meant to used wide open (otherwise what good is it?) would show the most issues from all those defects.

A longer lens, stopped-down, could probably have a bear turd smeared across it with a Mill Bastard File and it would still make a good picture. This would be the opposite of a long, stopped-down lens wouldn't it?

Good luck getting the exchange worked out.

[Daniel Unkefer]

OK I have one of those from him. Alot of them were obviously abused.
I would want the original barrel with the original cells, because at the factory Schneider would machine them, so that they were optimally spaced. Sometimes you can see where they have been machined, to make the optimum optical spacing.

BTW mine is quite sharp wide-open, although the DOF is thin as a sheet of paper (but that is what I had hoped to achieve). Great for shooting on the Plaubel Makiflex, in fact, the 150mm F2.8 Xenotar was one of the original lenses offered for the Makiflex.

[tbeaman]

Sorry, just noticed these last two posts. Thanks, Frank and Daniel. You both make excellent points I didn't, but should have, considered. I'm sending it back on Monday. Hopefully the replacement will be okay.

I actually already acquired a 240 convertible Symmar to steal the Compur II 5/2 shutter from. Daniel, thanks for the the reminder that I'll have to test it against the barrel mount to check for any spacing issues.

I love your Makiflex setup, by the way! Very jealous!

[john wood]

Also, don't split it just because the rear cell is in good shape; I've purchased 3 150's from him...and in each case the rear cell was in fine shape. Since they were used to photograph ammunition explosions and the like, it's the front cells that are hit or miss.

[BobCrowley]

I have one from the same ebay seller, now in a Compur 2, and another in a Copal 3 that I have had for a while. The cell distances are slightly different and as a result the FL is a little different. The both seemed reasonably sharp and similar, and I swapped cells between them (after marking the "right" ones) to see if I could spot any difference. I could not, shot on Efke 25 at infinity, see any difference. I also for fun tried using the 240mm Symmar front with the Xenotar rear, a "Symmatar" but, not much to write home about.

I'd like to get one more to put in a Compur 2 that I just restored, so I can have a stereo pair, but I think we are all bidding against each other, so I might wait and not bid up the price of the one currently listed. The seller told me last Summer that he had hundreds of these lenses. I certainly envy his surplus buying skills and luck.

By the way I found that not all the Compur 2s are the same: Some have a larger thread size than the Xenotar cells.I may turn an adapter for one since we have a machine shop.

The Xenotar I got was in the interrupted thread, helical Photosonics mount. In my case, the filter thread had a good dent in it, which I managed to repair well enough to use without cross threading.

http://new55project.blogspot.com

[Jim Galli]

It is non symmetrical.

For interest sake, I have 5 of these in the cupboard at work and have used them on the Photosonics 4E cameras. The 4E is a pin-registered 35mm high speed movie camera that can achieve 360 images per second. Pin registered means registration pins hold the film in alignment on the polished chrome platen while the shutter moves past. So the registration pins have to move backwards out of the way while the movement grabs the next set of perfs and pulls the next frame in. Once in place, the pins move back into the perfs to hold it in register for the next exposure. A small vacuum motor provides negative air pressure at the platen for perfect flatness. Imagine all of this happening 360 times in a second. The movement that did that job is nothing short of pure artisanship. Gorgeous!

So the 150 Xenotar's were only illuminating a half frame 35mm image 18X24mm. Sweet spot in the center. These lenses could resolve between 80 and 90 lpmm in that center area giving them Nikon like resolution (or better than) at 360 fps. Awesome machines.

It makes me sad that we'll never use them again. A LOT could go wrong with a film camera and you could still get product for your customer. Digital is very different. When it works it's glorious, and when it doesn't, you've got nothing. Big time nothing.

[Policar]

If anyone has one of these they ordered but aren't entirely thrilled with, I want to use one to build a sort of mini35 adapter to get super shallow focus video on my new camera. Since I'll only need to resolve 1920X1080 it needn't be the cleanest sample and no shutter needed of course.

[BobCrowley]

You might want to get one in the Photosonics mount to machine and match up to your camera. However, for even less money in your application, you might consider a Mamiya 150mm F2.8 and an adapter, or several other fast 150mm lenses made for 35mm. The unique thing about the Xenotar is the fairly large image circle that covers 4x5 and I think that is why it is somewhat sought after, along with other old lenses such as the Aero Ektar 7" f2.5, or the Pentac 8" f 2.9, as these all cover 4x5.

If you have a naked Xenotar and need the Photosonics mount, I'd guess you might be able to get one for a modest price.

http://new55project.blogspot.com

[Policar]

Thanks, I should have been a little clearer re: what I'm trying to accomplish, though. I've recently seen a weird amount of demand for "normal" lenses with super shallow focus for video, but no one has a good solution.

So I want to put a xenotar on a LF bellows, replace the ground glass with a microwax screen (I used to make these, much finer texture and stronger diffusion than normal ground glass), and then put a 77mm center filter on the xenotar (via eBay, can't afford one new) in accordance with how much fall-off my spot meter tells me I'm getting on my ground glass. Then attach a video dSLR to the rig with a 55mm nikor micro focused on the ground glass, and shoot away.

Should give an upside down image with a focal length equivalent to like 30mm on APS-C? But potentially with the equivalent depth of field of around f0.5.

Kind of a silly endeavor, which is why I probably won't bother.