Glue Separation?

[cblurton]

I've been looking for a lens for my new Shen-Hao 4x5 on eBay and have come across several statements similar to this one over the course of the past month or two (from an auction for a Rodenstock Sironar 150mm f/5.6 with no reserve and a starting bid of $49.99):

"This Lens is in Excellent condition with no blemishes on the casing. There is glue separation within the lens which can be overhauled, however this minor flaw has NOT interfered with picture quality!"

First, it seems to me that a lens cannot be in "Excellent" condition if there is glue separation among the elements. Second, it also seems to me that such separation WOULD interfere with picure quality, at least lowering the amount of light that gets through the lens to the film. Finally, I wonder what an "overhaul" of such a lens would cost and if it is so prohibitively expensive that the lens isn't worth buying at any cost?

Best wishes,

Craig

[Steve Hamley]

Unless it is an expensive or unique lens, stay away. John Van Stelton at Focal Point, Tim Sharkey at LensN2shutter, Ultra Flat can recement elements, but John charges about $180 per "joint". which would be the price for the Sironar (cemented elements are doublets).

So you'd need to get about $250 off the price of a $250 lens to break even after shipping and such. And that's assuming everything else is perfect, always a risky assumption with old lenses.

Oh yes, and that assumes only 1 cell has separation...

Steve

[Capocheny]

Steve,

I've heard that they had to heat these lenses up at high temperatures in order to separate the elements. Then, they glue them up again.

Is this true?

And, one of the risks of the proceedure is that the glass can crack. Is there any substance to this?

Lastly, I wouldn't think there would be any way possible to predict the rate of separation once it starts, is there?

I had a "separated" Rodenstock 90 f4.5 back when I first got started in LF. I was told the lens might just as well be tossed into the trash. I did, however, keep the Copal 3 shutter! :) The cells did go into the recycling bin!

It sure did hurt to do that! :>|

Cheers

[jnantz]

capocheny

there is info on lens recementing on skgrimes website (http://www.skgrimes.com/popsci/index.htm).
pretty interesting stuff.

-john



Steve,

I've heard that they had to heat these lenses up at high temperatures in order to separate the elements. Then, they glue them up again.

Is this true?

And, one of the risks of the proceedure is that the glass can crack. Is there any substance to this?

Lastly, I wouldn't think there would be any way possible to predict the rate of separation once it starts, is there?

I had a "separated" Rodenstock 90 f4.5 back when I first got started in LF. I was told the lens might just as well be tossed into the trash. I did, however, keep the Copal 3 shutter! :) The cells did go into the recycling bin!

It sure did hurt to do that! :>|

Cheers

[Kevin Crisp]

It isn't worth regluing a lens like this, get one in good shape. I would NEVER buy one with separation without seeing the issue anyway. I have had 1950's vintage Schneiders with a little snowflake star of separation and it had was to drive down the value of the lens, anything more separation than that I would pass. No, heating will not eliminate the problem, this doesn't fix balsam faults and it certainly isn't going to work with the post-Balsam synthetics.

[Capocheny]

Hi John,

I've always wondered about the process of repairing a separated lens so I'll definitely take a peek at the link.

Thank you...

Cheers.

[Steve Hamley]

S.K. Grimes no longer does the operation, they'll refer you to John Van Stelton at Focal Point. Lenses cemented with Canada balsam are warmed, which is not much of a risk to the lens. Lenses cemented with modern cements are dipped in solvent to dissolve the cement.

Recoating involves heating the glass, which can crack the glass, but hey, if it's coated it survived once.

I have a 9-1/2" Gold Dot Dagor that has a tiny amount of separation in the front glass - hardly visible unless you remove the cell from the shutter. I haven't bothered to fix it since stopping the lens down any at all will cover it. It hasn't gotten any worse in the year and a half or so I've had it.

Steve

[John Kasaian]

On old lenses it is often a matter of balsam seperation---a ring of crusty looking stuff like dried mucilage around the very edges of the lens. It is usually obscured by the aperture blades when the lens is stopped down for picture taking---so no biggie. Turner Reichs for example, often exhibit this malady.

Of course, this condition isn't going to get any better (given enough time I suppose you wouldn't even have to warm the lens to seperate the elements for A reglue ;-)

Otoh, you can use it to bargain the price down (waaay down) This is a good thing if you're on a tight budget just so long as you know what you're up against. As a general principle, I don't like messing about with such glass---its doubtful you'll ever be able to get your money out of it and I'm not into the Sally Mann look---there are too many really good old lenses out there to spend your $$ on. Be patient.

[Capocheny]

Hi Steve,

Thanks for the info... then that means I should have sent the 90 f4.5 in for re-gluing. I was under the impression that it wasn't worth it and, therefore, it ended up being recycled! Even the manufacturer said it was going to cost more than it was worth at the time! And, that there were no guarantees.

Such is the learning curve for a newbie at the time!

So, the risk of the glass applies only for re-coating jobs. Good to know. :)

Thank you

Cheers

[Steve Hamley]

Well, the manufacturer may be right. A used lens in really good shape is worth say 50% of a new one, so you have to assess the $200 against what a good used example would cost - minus the shutter.

A used Copal 0 or 1 would sell for roughly $150 - $225, and a repair would be $200, so for a typical lens I'd sell the shutter off the funky lens (or use it for something else) and take that off the price of a used replacement. If the replacement minus shutter price is anywhere near $200 just hit the easy button and do the replacement - don't have to wait, risk the lens, ship pieces all over the country...

If you have a 19" or 24" Gold Dot dagor, that's a different situation altogether.

Steve

[cblurton]

Thank you all very much for the feedback. It was a learning experience. Based on the comments, I've looked up the S.K. Grimes (http://www.skgrimes.com) and Focal Point (http://www.focalpointlens.com) Web sites and decided that if I can get a lens like that described for $50 or less it might be worthwhile to have it repaired. Otherwise I'll pass ...

Craig

[Donald Qualls]

Another option for lenses with separation -- I've read about this being done on Sonnar lenses for Leica mount cameras, but it seems applicable to LF as well. If you're up to disassembling the glass from the cells, and the separation is the clean, "soap film" appearance type (what happens with modern cements when they lose adhesion on one glass surface), you can remove the glass from its cell, wick an oil with matching refractive index into the separation line (carefully, so it fills rather than trapping a bubble), button everything back up, and go enjoy your bargain lens.

The effort involved is non-trivial, but it's a great deal less work (and risk) than recementing, and according to the source of the report I read (Nicolas Douez, over on nelsonfoto.com) it has worked very well for him (on lenses that were worth the effort, that is, very good if not for the separation).

[erie patsellis]

I've done the oil trick on a 150 sironar I got (really cheap) worked like a charm, bit of work, and I cleaned all the elements while I had them out, cleared up a slight foggy look through the lens. I have a componon 360 5.6 that has one little snowflake, about 3/8", on the rear element. Damned if I can see any effect on 8x10 negs shot with it, and it sure brought the price low enough ($50) that I don't mind using a packard on the front of it. Of course a month later, I bought a 360 5.6 symmar, so now th 360 is permanently mounted in a toyo lensboard for the 4x5.


erie