Help! My lens elements are separating

[cotdt]

I have a Schneider Angulon and the front lens elements are peeling apart. I can see the air pockets forming. What can I do to fix it?

[Colin Graham]

Well, there's this (http://www.skgrimes.com/popsci/index.htm)...

[cotdt]

Well, there's this (http://www.skgrimes.com/popsci/index.htm)...

Seems high-tech... and expensive (I only paid $30 for this 90mm f/6.8 lens). I'll try to do it the DIY way. What glue should I use?

[John Schneider]

A UV-cured cement made for re-attaching car rearview mirrors is good for DIY-ers.

[Kevin Crisp]

Are you sure the glass is separating from glass, as opposed to Schneideritis? I ask because normally separating doesn't look anything like little bubbles.

[cotdt]

Are you sure the glass is separating from glass, as opposed to Schneideritis? I ask because normally separating doesn't look anything like little bubbles.

What is Schneideritis?

[cotdt]

A UV-cured cement made for re-attaching car rearview mirrors is good for DIY-ers.

Wow! Are you Mr. Schneider himself? Did you design my lens?

[Colin Graham]

cotdt, the link was a DIY way. V-blocks and glue doesnt really seem all that hightech.

[Ole Tjugen]

The Angulon is a dangerous one...

The two inner elements in each cell are only supported by being cemented to the (oversize) outer element. Also, like most wide angle lenses, it's extremely sensitive to decentering.

With lenses where all elements are ground down to the same diameter it's fairly easy to get the cemented cells well centered. The Angulon is practically impossible.

If they are really separating and it isn't just "Schneideritis", get another one.

"Schneideritis" is a bubbling in the black paint on the edge of the lens, which has no detrimental effects. It's fairly common on Schneider lenses, while Rodenstock seems to be more prone to cement failure.

[Toyon]

Grimes doesn't do recementing anymore. Try www.focalpointlens.com.

[cotdt]

Here is a picture of my lens. As you can see, there is a bubble in the center and at the sides where the black paint is.

http://img174.imageshack.us/img174/8642/dsc05014xf2.jpg

What seems to be the problem? This is the only lens I use, and I am worried that I am not getting the best quality possible out of it. My pictures seem alright, though.

I've owned dozens of old Nikon lenses never with these kind of problems. I don't think Nikon lens elements are even cemented together. Why did Schneider have to cement their lenses?

[Peter K]

What seems to be the problem? This is the only lens I use, and I am worried that I am not getting the best quality possible out of it. My pictures seem alright, though.

I've owned dozens of old Nikon lenses never with these kind of problems. I don't think Nikon lens elements are even cemented together. Why did Schneider have to cement their lenses?
When the there is no loss in quality and no increase in separation you can use this lens as usual.

Compound lenses are made from different pieces of glass with different shapes and refractive index. Also the air space is a lens, but only with refractive index 1.00. When you look at a schematic drawing of your Nikkon lenses you will see also this lenses are cemented. This is a common practice since the first achromatic lens was made.

Peter K

[Kevin Crisp]

I would say based on your photo that you do have some edge separation. I can't clearly see the bubble in the middle but if it is that wedge shape then I think that is separation too. This is a relatively older Angulon, I think you can find a newer one for less than the cost of having this one recemented. If it works, though, use it. Given that the individual elements are not all the same diameter, I can tell as an amateur lens repairer that it would be really, really difficult to separate and reglue this and preserve the centering which is really important in a wide angle. Having a professional redo it would probably run $250+. I would only do that if I knew I had an exceptional performing example of this lens, which isn't all that likely on one this age. I am sure Focal Point can handle this in the US, there is a company in England that does a nice job too.

[Dave Moeller]

As has been noted, if the lens is working for you, go ahead and use it. You're probably stopping down quite a bit, so the edge separation isn't impacting your images. It's hard to tell if there's anything going on in the middle of the lens from the picture you posted.

As to Nikon: I can't think of a single Nikkor that doesn't have cemented elements. Lens manufacturers have been cementing elements together for over a century. The glues that they use have improved dramatically, and element separation doesn't seem to be a problem on newer lenses. (Of course, none of them have been around for 100 years yet.)

Best of luck.

[John Koehrer]

Since you don't have a lot to lose and if you feel like experimenting, Pull the front group & soak it in acetone to separate the elements. Make sure there's no residue on them & use "crystal clear" to recement them.
Don't do this under flourescent lights---It's the UV that begins the curing process.
The technique for recementing the elements is kinda finicky so a lot of care is needed.
You apply one small drop of cement to the concave element & allow it to settle for a few minutes. You don't want to have any air bubbles in it. Carefully set the convex element in place & use it to spread the glue over the entire surface of both sections. Wipe any squeezeout off the lens as best you can & set it back into the housing. The housing will hold it in alignment for you. Expose it to UV for a day or two, sunlight or flourescent makes no dif.
BAD stuff--- The Crystal Clear is a permanent solution. If it not aligned correctly the group will no longer fit back into the housing and Acetone IS NOT a solvent for this cement.. Don't ask me how etc......
If you've done the above you're gonna figure out that you need to repaint the edges of the group. Hmmmmmm....Press the group out of the housing????? The CC may still have a little squeeze out & stuck to the housing. If it's not too much you can press it out. If it is too much, you're not going to paint the edges & can consider yourself done. If it pops out mask the front & rear surfaces & use a light coat or two of gloss black from a rattle can to finish it up.

[Ole Tjugen]

... Carefully set the convex element in place & use it to spread the glue over the entire surface of both sections. Wipe any squeezeout off the lens as best you can & set it back into the housing. The housing will hold it in alignment for you. ...

As I've explained already, there is no housing in Angulons!

Only the outer element is supported by the housing; the two inner elements are only supported by being cemented to the outer element.

So: Since attempting to repair it would most likely ruin it, I suggest you use it while it lasts. Use that time to find a replacement; preferrably a somewhat newer one. You can try to find one with a bad shutter; or even one without a shutter since you already have one.

addendum: See pictures of a de-cemented Angulon 90/6.8 below. The inner two elements are missing from the front cell - the cells should have looked the same except for the mounting threads.

[CG]

Optic Karma Alert

This one isn't a DIY project. I'm biased - I think old Angulons are a little piece of history - and I'd hate to see one destroyed in the name of economy. I think your photographic karma will be increased if you to use it till it's not shooting well, then get it fixed right or sell if off to somone who will.

C

[chilihead]

If your lens elements are separating, perhaps you should take them to a marriage counsellor... this works at least 40% of the time...