Strange "coating" on Summar

[kestas]

hi
i have a 1935 leitz summar and it has strange "rainbow" on front element. it looks like a coating, but not like common single or multi-coating of less or more modern lenses. what can it be? a sort of glass oxidation? damaged coating?
p.s. yes, i know, all summars left factory uncoated, but some of them was coated postwar.

 

[Bryce]

I don't claim to know exactly what you're seeing on your lens, but I do know a little about the history of lens coatings.
In the astronomy community, there are records from before the turn of the 20th century of scientists noticing that old, tarnished telescope objectives gave brighter and contrastier images. From that was born coatings, or artificial tarnishing.
Perhaps this is what you are seeing?

 

[DeeCee3]

What an odd coincidence! I, too, have an antique E. Leitz pre-war lens with what I have always assumed was a thin oily film inside the lens. I've had the lens several years but have never used it. I saw your post, pulled my lens out of tbe case and see that it, too, is a 5 cm Summar (with the old-style stop numbering) and a 347xxx serial number.

Is it possible someone can shed more light on this, or is it simply an anomaly?

DeeCee

 

[xayraa33]

it looks like "blooming" of an old uncoated lens.
a natural coating forming on the glass.

 

[ravid905]

Check out auction number 280110766282 on ebay, it seems like it may be similar to what is happening to your lens. It's not an answer to your question, but maybe if you ask them they might be able to give you an answer.

 

[kestas]

thank you all for your replies
.
DeeCee, try this lens, you'll not be dissapointed

 

[oscroft]

I think the "rainbow" colours will be caused by the uneven thickness of the natural bloom built up on the lens - different thicknesses refract and reflect different colours differently.

 

[DeeCee3]

Thanks for the thoughts on the "blooming" of the old 50 Summar. My involvement with cameras goes back a long time and I knew I had seen this phenomenon before on old lenses. I have an Ikon "Nettar", also from pre-war days, and its glass also seems to have this psuedo-coating.

And, yes, Kestas, I intend to use the lens very soon...this weekend, in fact. I've been recuperating from a stay in the hospital but as soon as my strength returns enough to get outside, I'll putthe Summar to use.

Thanks for all the interest.

dc3