Eyepiece cement

[moriniboy]

Can anyone recommend a good cement for use on eyepieces.

One of my older TAL ones started to de-laminate around the edges and it was affecting my views, I have therefore split it and cleaned off the old cement.

An internet search comes up with a cement called G-S Hypo which can be used for optical uses but I'm unsure if it will be good enough.

[alan potts]

Moriniboy,

I have to give it to you that is a question I have never seen asked before. Have you tried asking an optician?

Alan.

[Macavity]

The much fabled: http://en.wikipedia.org/wiki/Canada_balsam ???

[John]

The much fabled: http://en.wikipedia.org/wiki/Canada_balsam ???

I used to use that stuff to prepare microscope slides when I was a lot younger. I didn't know you could still get it.

It might well do the trick though

[Moonshane]

it can yellow with age based on my own use with insect specimens maybe giving a light coffee tint ? :0))

[AndyH]

I looked into this about a year ago, as I have a few eyepieces(plossl's) and a 50mm finder who's doublets are starting to de-laminate slightly. Sadly the details I saved are on another pc, who's power supply unit is knackered. I'm sure the stuff that caught my eye was Norland NOA60 ?

Out of interest, how did you safely separate the doublets, as I've read of a few different ways?

As for getting them cemented back together again, I think the only slight difficultly would be fabricating a small accurate jig, to hold the lenses 'true' and aligned. I hadn't thought that far ahead though to be honest, so difficulty may be overstating it

Most interesting thread. Shall follow it with interest.

Andy.

[moriniboy]

That Norland stuff ticks all the boxes but it costs more than the ep!

Going to get some G-S Hypo and give it a go.

Re splitting the elements I was a but of a Neanderthal and just used light pressure with a Stanley knife blade, it separated easily (Note - I pre marked the lens alignment before splitting it)

[moriniboy]

Just received the following response from the manufacturers of G-S Hypo:
 
Hello Nigel,
Yes, G-S Hypo Cement is frequently used for lens and optical repair. It is also used for the assembly of lenses into housings by several manufacturers.
Please see the attached User Guide for more information.
We will be happy to answer any other questions.
 
Sincerely,
Kathye Simon
G-S Supplies, Inc and www.ToolsGS.com
 
1150 University Avenue, Suite 5
Rochester, NY  14607  USA
toll-free: 800.295.3050
ph: 585.241.2370
fax: 585.241.2375
email: ksimon@gssupplies.com
web:  www.gssupplies.com

[moriniboy]

Used the G-S Hypo last night and it needs 24 hours to cure.

Weather gods permitting I will get a clear spell tonight.

Tried it out on an old 0.965" ortho with the same problem before moving onto the TAL, before and after below.

[Don Pensack]

Well, it looks like you've resolved this.

But, in the future, be aware the cement has to match the refractive index of one of the two cemented elements in order to not act as a separate optical element itself, even if, an albeit virtually invisible one.  But when the refractive index of the cement doesn't match either element cemented, you can get reflections from the two surfaces, as well as the two cemented glass surfaces.

[moriniboy]

First light achieved using the newly cemented ep and the results are not good......

On axis looking at Jupiter and the moon terminator there are no problems, just as sharp as I remember and identical to a similar ep used as a comparison.

However off axis as the target drifts toward the edge is a different matter with increasing levels of misting and aberration I would say that G-S Hypo is not recommended for this type of repair unless you have no option.

In the interest of progressing this thread further I'm going to get some Norland and see how that goes.

[DRT]

I would say that G-S Hypo is not recommended for this type of repair unless you have no option..

With all due respect, as this appears to be your first attempt at this highly technical and intricate operation I think you at least have to consider the possibility that the cement is not the cause of the problem

[Peter Drew]

It might be worth trying oil spacing as per some current objectives. I have also successfully seperated cemented achromats by bringing them to the boil in a saucepan with a foam liner to protect the glass.