Re-cementing Summitar elements.

[Dez]

I have a lovely old 1939 vintage Summitar, which is in great mechanical shape, and the glass is completely free of scratches, but I have a separation problem in the front elements.

I have some nice fresh Canada balsam, and I did this repair with a Summar once upon a time, but I have forgotten some key points. I suspect I will need to bake this lens a fair bit to get the elements out of the front ring- can anyone comment on just how hot that needs to be, and whether that will destroy the paint on the identification ring?

As I recall from the Summar, once the cemented pair gets to a critical temperature they come apart very easily, which implies a bit of handling with oven mitts. I believe laquer thinner does a good job on the remaining balsam to prep the elements for reassembly. (It WAS Canada balsam in 1939, right?)

I would greatly appreciate some advice from someone who has done this particular job to lesen my chances of totally screwing up from a certainty to the merely probable.
😕

Cheers,
Dez

 

[John Shriver]

The groups are peened into the mount, not just held in by Balsam. You would need to machine off some metal to get them out.

You may be able to repair it by just baking the offending pair of elements, and hope that the Balsam reflows to where you want it. I did this on a Summar and improved it from hopeless to usable. But it was a $35 lens, so who cares.

However, one element of each group in the front of the Summitar is very thin in the middle, and deeply curved at the cemented joint. That's probably a recipe for a higher than usual risk of cracking when you heat them up. It will also be a problem that the Balsam would probably try to run to either the edges or the center.

Hard to say what to recommend, DIY, or sending it to Focal Point Lens or CRR Luton.

 

[Dez]

Re-cementing Summitar elements

Re-cementing Summitar elements

I got away with gently baking the front group, which reflowed the balsam as you mentioned. It lasted about a year, but the separation reappeared. This time when I tried it again my luck ran out when the balasm started turning brown. I have worked with Focal Point before and was happy with their work. I am concerned that the cost of repair could easily exceed the value of the lens- do you have an idea of what it would be?

Do you know approximately how much metal I would need to remove if I were to cut away the peening?

Cheers,
Dez

 

[John Shriver]

http://www.angelfire.com/biz/Leica/summar.html

That show's what's involved on a Summar. Summitar would be similar.

It's not likely a cost-effective repair. I'm sure both vendors could quote an estimated price. On the other hand, a Summitar is a lovely lens, if the glass is in A-1 shape, it might be worth the risk. (The procedure can also fail dismally with a cracked element.)