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Some strange reflections...
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PostPosted: Tue Oct 26, 2010 9:08 pm    Post subject: Some strange reflections... Reply with quote

I did not see them in the viewfinder Shocked



PostPosted: Tue Oct 26, 2010 9:14 pm    Post subject: Reply with quote

Looks like a broken/separated cementation for me.. (dont know if the pancolar has got one cemented element)

Cheers
Henry


PostPosted: Tue Oct 26, 2010 9:27 pm    Post subject: Reply with quote

Indeed we could think these are Newton rings, but I can't see them with the naked eye, and I think No-X did not see such reflections too. I'm wondering how they could come here Question


PostPosted: Wed Oct 27, 2010 11:52 am    Post subject: Reply with quote

Not separated element, the pancolar has not glue between the first and the second elements.

That reflexions are present in some septon lenses. I saw it in old skopar for medium formart lenses too. Old people called it as "iridised lens" And not able to be fixed.

Casuality, or not, I never saw it in japanese lenses. Well is tru that I never try be a collector of them.

Incidence in pics? I don't know. Perhaps if you use the lens can eliminate the doubts.

Rino


PostPosted: Wed Oct 27, 2010 12:35 pm    Post subject: Reply with quote

Maybe this helps.
It is in German, but Google translator can be of help.

The effect can be due to uneven coatings on the lenses.

See:
http://www.mikrofotografie.info/Physikalische_Aspekte_von_Ring/physikalische_aspekte_von_ring.html

"Die Schichtdicke einer Linsenvergütung beträgt etwa 1/4 der durchschnittlichen effektiven Lichtwellenlänge, entsprechend etwa 140 nm (Netzwelt-Lexikon, 2006). Ungefiltertes Weißlicht mit einer Kohärenzlänge von etwa 1000 nm kann daher Interferenzerscheinungen an Linsenvergütungen hervorrufen, wenn die Vergütung ungleichmäßig aufgetragen ist und deren Schichtdicke geringfügige Schwankungen zeigt. Es ist bekannt, dass ungleichmäßig vergütete Linsen Newton-Ringe zeigen können (Netzwelt-Lexikon, 2006)."


PostPosted: Wed Oct 27, 2010 12:50 pm    Post subject: Reply with quote

and German wikipedia:

http://de.wikipedia.org/wiki/Antireflexbeschichtung

"Die Antireflexionsschichten stellen zudem hohe Anforderungen an die Gleichmäßigkeit der Schichtdicke. Denn ungleichmäßig vergütete Gläser zeigen Farbverläufe oder gar Newtonsche Ringe und sind daher für viele Anwendungen unbrauchbar."