Can anyone separate, clean and re-cement eyepiece elements?

MortonH · #1 13-01-2023, 12:46 AM

I bought an original Celestron Axiom 15mm from the US on ebay but it has some internal haze. On taking the eyepiece apart I discovered that the haze is inside the uppermost cemented doublet element so I can't get to it. I've read some articles on Cloudy Nights that describe various ways of separating the elements, cleaning them and then re-cementing them. I reckon if I tried this myself I'd probably damage or destroy the lenses so I'm wondering if anyone here has done this and might be prepared to try to fix my eyepiece (for a fee, of course). It also seems that the adhesive for re-cementing is kinda expensive so it wouldn't make sense for me to spend the money on such an old eyepiece, but if someone already has the necessary materials lying around...

Please send me a PM if you can help.

bojan · #2 13-01-2023, 06:13 AM

Separation should be easy, just immerse the doublet into xylene or turpentine or acetone, and apply the lateral force some time later to separate elements.

For gluing, use Canada balsam (yep, apparently expensive).
Some people used UV (blue LED) hardening glue, it is available on ebay for couple of $.

Saturnine (Jeff) · #3 13-01-2023, 09:49 AM

Can't help with your problem MortonH but I am interested in knowing if UV setting, cemented lens can be separated as I have a reasonably expensive eyepiece that has , what appears to be, the edge blackening seeped into the cemented join between the 2 elements of the eye lens. Had tried soaking in acetone for several days but that didn't seem to work .

MortonH · #4 13-01-2023, 09:59 AM

My problem is that I live in a small apartment so don't have the space or equipment (e.g. UV light) to try this myself.

MortonH · #5 13-01-2023, 10:01 AM

Quote:

Originally Posted by Saturnine

Can't help with your problem MortonH but I am interested in knowing if UV setting, cemented lens can be separated as I have a reasonably expensive eyepiece that has , what appears to be, the edge blackening seeped into the cemented join between the 2 elements of the eye lens. Had tried soaking in acetone for several days but that didn't seem to work .

Here are some of the CN threads I found - seems gently boiling in water can separate them although I'm not sure how you stop the elements bouncing around in the water and getting damaged.

https://www.cloudynights.com/topic/3...-re-cementing/

https://www.cloudynights.com/topic/1...o-be-cemented/

https://www.cloudynights.com/topic/5...evue-paracorr/

Saturnine (Jeff) · #6 13-01-2023, 05:43 PM

I'm aware that the old Canadian Balsam cemented lens can be separated by gently heating and sliding the elements apart then cleaning off the residue with acetone but don't know if UV cured cement ( resin ) can be separated, was lead to believe they couldn't be once set .

Stefan Buda · #7 13-01-2023, 07:07 PM

Some of the adhesives used for cementing seem to resist any solvent you throw at them. As a last resort I heat them very slowly in a small oven until the cement starts to decompose and then I try to separate them while still hot in the oven. Larger doublets tend to crack, due to the different thermal expansion of the elements, before the cement decomposes.

leon · #8 13-01-2023, 09:21 PM

It is something you should try yourself, things can go wrong and if you stuff it up you are to blame.

For someone else to have ago unless they are experts is not a good choice.

I did a Filter change on a new Canon 5D once and it worked, but it could have gone sideways.

If someone else dose this for you expect the risk.

I have seen videos of how high end optical lenses are put together it is a precise procedure and not for the faint hearten.

Having said that be brave and have a go as bojan said, what can go wrong, you stuff it or fix it, no big deal.

It is only a Lens at the end of the day

Leon

MortonH · #9 13-01-2023, 10:04 PM

I think I'm guaranteed to stuff it up, which is why I don't want to try!

I contacted the ebay seller and they've agreed to refund my money so if someone has done this before and wants to have a go I'll accept the risk that it goes pear-shaped and I end up with a Celestron paperweight.

If not I'll leave it alone and accept its shortcomings.

dannat (Daniel) · #10 14-01-2023, 07:38 AM

ive done a binocular element w balsalm, its horrible sticky crap which is hard to clean off without getting messy, then reset elements with the UV cement..its [UV cement] very easy to apply, very diff to remove...im guessing the fogging is caused by the cheap adhesive the manufacturer has used, i dont have any of the UV lens adhesive

ps use oil to join lenses,

RAJAH235 · #11 14-01-2023, 11:41 PM

Hi Morton,
I'm not sure if these people will be able to help but it can't hurt to ask them.
Maybe even go there & show them the eyepiece in question & they can see the fault.

Like I said, I dunno, as I've never used them.

Link > https://www.optomech.com.au/

MortonH · #12 15-01-2023, 12:21 AM

Quote:

Originally Posted by RAJAH235

Hi Morton,
I'm not sure if these people will be able to help but it can't hurt to ask them.
Maybe even go there & show them the eyepiece in question & they can see the fault.

Like I said, I dunno, as I've never used them.

Link > https://www.optomech.com.au/

Thanks, I'll give them a call.