Separated Elements

[iangreenhalgh1]

Hi folks

Is it possible to repair a lens that has some separation? i have heard of people putting them in the oven, is this an old wive's tale or does it work?

[luisalegria]

I have actually tried this - used an old toaster oven.
It didn't work for me, the separation just changed shape.

The proper solution in theory would be to re-separate the elements and re-cement them, which is apparently not out of the question for a novice, if one takes care to keep the elements correctly aligned while they set.

What I wonder about though is the effect on coatings. Unless I miss my guess heating elements may damage them badly.

[Sevo]

Re-cementing through heat does not work for the lenses we usually talk about - Canada balsam, where mild warming did work, was only used up until the thirties to late forties, and the plastics that succeeded it tend to go yellow or brown before they separate for good rather than re-join.

[iangreenhalgh1]

Thanks guys, I'll pass on the diy treatment then, I don't fancy boiling elements in solvent to separate then re-cement as I doubt I'd get em centred.

[visualopsins]

Off and rejoining of an objective lens

Ultraviolet Curing Optical Cements and Photopolymers

[Attila]

[iangreenhalgh1]

Thanks Attila, I had seen a Distagon with severe separation going very cheap, I will pass on it.

[ZoneV]

I have made first experiments with canada balsam with an old Agfa lens. But the result was not good enough - but I think with some refinement it could be DIY done.
Thinking about a procedure to work without loosing to much of the heat whilst taking the two oarts together, probably near some heating element, to get more time to align and get the canada balsam every where.
Or try to get better amount of canaca balm onto the lens.
Or take UV cureable glue - so I have long time to adjust, and when I am think I am ready I could use the sun for curing. I think this way would be much easier.

[bob955i]

I have a Flektogon 35 that had what appeared to be a fingerprint inside a cemented doublet - I marked the doublet sides for some degree of correct re-alignment then used a hairdryer to gently heat the doublet until the balsam melted enough to separate the two elements. The balsam was then cleaned off, a tiny spot of watch oil applied to the relevant side of one element, the other was then fitted to it and slid around to spread the oil. The previously made marks were then re-aligned and the doublet refitted. The oil layer is so thin that it's effectively clear.

Worth a try if the lens is cheap or as an experiment on one that it doesn't matter if it doesn't...