Archived posting to the Leica Users Group, 2005/01/15

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Subject: [Leica] A little help please
From: weiljr at earthlink.net (joe weil)
Date: Sat Jan 15 17:47:32 2005

Hello,
 I am hoping that greater knowledge of this group will give me some insight
to what I noticed on my negatives (Tri-X, shot at 400). I was shooting at
night with an R-8 and an older Summicron R 90 (Canada, # 2,463,XXX). In the
negatives shot with this lens, I noticed a secondary image of a bright
light source (a streetlight) in the negative as well. The street light was
positioned in the lower right hand corner of the negative and the secondary
reflection was located in the upper left corner so it seems to be symetric
about both the x and y axis.  The secondary reflection was obviously
stronger as exposure time was increased. I spot metered off the street
light, opened up 2 stops and bracketed a couple stops in both directions. I
believe the aperture was somewhere between 2 and 4 and was constant when
the exposures were taken. There was a Hoya 81A filter in front of the lens
during the exposures. 
I checked the lens and filter to see if they were clean and there was
nothing obvious on either. 

What would cause this secondary reflection, the lens, the filter or both?
Has anyone else experienced this phenomena?
I am planning an experiment to shoot with this lens at night with a single
bright light source at a small, medium and large aperture, with and without
the filter. Metering would be performed the same as I did above with an
obvious slant toward overexposure. 
If you have any other ideas of things that I could try to figure it out,
please let me know.
Thanks
Joe 




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