Originally posted by Just1MoreDave It should be possible. Some solvent to get the elements apart, cleaning, then recementing. How hard can it be? Of course the cement needs to be something that won't alter the optical properties of the lens. The lens coatings need to be intact. It needs to end up with no air bubbles and be a consistent thickness. The lenses need to maintain their alignment. It's like a lot of lens repairs - either you pay someone a lot of money or wing it yourself.
Well, it all is very easy...
First you have to disassemble the lens, take out the cemented elements and bake them in the oven. At around 200 deg Celsius, the glue will get soft and you can separate the elements completely. BEFORE doing that, you will have marked the rotational position of the two lenses with some pencil.
Then you have to clean the residue of the old glue - acetone might work.
Then you need some optical glue. In the long and distant past, opticians used Canada Balm for that. It works - but it takes weeks to cure and I would never let that stuff come near me. It sticks everywhere and is very hard to remove. What you need is modern optical glue, that is cured with UV light. (Edmund Optics is the place to go
Edmund Optics)
First build a small rig, that allows complete symmetrical assembly of the two elements. Put only one or two drops of the glue on the lower element and put the second element on top (you have made notes or photographs during disassembly, so you know which side of which lens faces the other, ofcourse), whiggling it carefully around to squeeze all the air bubbles out. There might be some left between the elements and you start all over or you simply ignore some small bubbles (but you won't ignore any dust!).
Let the whole assembly settle for a couple of hours and see, whether the remaining air bubbles get out. Also be sure, that the two lenses are rotated correctly and the pencil marks match!
If everything looks nice, get your UV light and cure the glue.
If that is done, you are nearly done and you can reassemble the whole lens.
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Now you know, why commercially this is only a repair that will be done to really expensive lenses. Even a repair shop will have to go through the whole effort and that takes much time. I personally would not make such a repair for such a cheap (comparatively) lens - perhaps for my 600mm Apo Schneider-Kreuznach, but not for the old M pancake...
Ben