50mm Summicron Type IV Rigid Problem

[Rapierwitman]

Hi

I have an old 1957 Type II 50mm Summicron that is in very good condition.

Both the barrel and front and rear elements are perfect, however on the inner elements there are these odd concentric circles in the middle. They look almost like perfect circular wear marks or perhaps a deterioration of some sort. They don't effect the lenses performance in any way though.

In all other ways a perfect 56 year old lens, but need to know what this issue is and how to fix it. 😕

Picture attached and any advice would be greatly appreciated.

Thanks

 

[Jerevan]

To me, it looks like delamination of the lens elements (they are glued together, most probably with Canada Balsam, considering the age of the lens). They need to be reglued in the long term, but in the short you can use as it is, if you don't see any effect on the performance. John at www.focalpointlens.com does good work with these things.