Summicron 35 v.4 rainbow effect inside

[pgk]

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I've just bought a 35 Summicron v4 which exhibits what was described as 'balsam separation' inside when viewed from the rear side. This manifests itself as a rainbow effect, but I'm far from convinced that it is in fact separation. The 'problem' actually looks very much more like Newton's rings - an interference pattern caused by reflection of light between two very close (rather than cemented) surfaces. Looking at the lens diagram (Puts) I see that this might possibly be the case and wonder if its caused by marginal misalignment of two glass surfaces which are not in fact cemented together. Does anyone know whether the v.4 Summicron has two such surfaces (I do seem to vaguely remember reading something about this being possible, but cannot remember where nor find it by searching)?

 

FWIW my preliminary shots indicate little wrong in the images so I'm not overly worried (it is a 'user' lens), but it would be interesting to know. Focus is not entirely smooth so I suspec that the lens may have suffered a drop or knock at sometime which would explain things quite well.

[henning]

That's separation. Resolution is generally not affected, but it will increase the incidence of flare and will lower contrast, but the former is of course is dependant on how and where you point it.

 

It can generally be fixed, but as you noted, is not always a problem.

 

Henning