How to fix balsam separation on a Canon 50mm 1.4 LTM

[lukx]

Hi all,

I have this cosmetically very nice lens with very few marks on the glass. But upon close inspection I found balsam separation around the edges of the rear doublet, which does not show the famous rainbow reflections but rather looks like a transparent film on the glass. Since I took out the rear group for close inspection, I know that it is not in fact oil on the glass.

The effects of this separation can be seen in the out of focus highlights, so it does have an effect on the images.

I wanted to sell the lens, but its value is greatly diminished due to the separation. This got me thinking if I could possibly re-cement the lens elements.

Does anyone know which type of cement was used for Canon lenses of that period? Was it still Canada Balsam?

I am asking this because the type of cement determines how easily the elements can be fully separated and cleaned. Also, Canada Balsam is readily available online, with many guides detailing how to perform a successful re-cementing.

Has anyone here performed such an operation? Would you think it's worth trying? Worst case would be an unusable lens I assume, i.e. when I succeed in separating the elements but fail to re-cement them correctly.

Any input is welcome. Thanks in advance

 

[santino]

Since any input is welcome I‘ve heard that it should be possible to gently heat the lenses on absolut level ground. The higher temperature should cause the lenses to re-cement. I haven‘t tried it yet and it sounds risky.

 

[Beemermark]

I've heard that warming the optical glass at very low temperature ~200 deg F or a bit warmer can separate the glass. It can also (if your lucky) make the glue liquefy and refill the entire glass. Boiling in distilled water also works. Use slide preparation glue to re-cement them. https://www.homesciencetools.com/product/slide-mounting-fluid-1-2-oz/

 

[Sonnar Brian]

Post some pictures of the elements in question. Unless the separation is really bad, you will probably make things worse trying to do this as a first-time operation.
Most likely a lens of this period uses Canada Balsam. Synthetic cement of the time was not very good, many West German Zeiss lenses from the later 1950s and 1960s suffer from separation. The eariler ones, using Canada Balsam - are usually in better condition.

 

[james.liam]

Not an expensive lens so it's cheaper to find one in better condition than go and repair the one you have. Sell your old one for parts.

 

[Sarcophilus Harrisii]

Superfluous post.