Archived posting to the Leica Users Group, 1997/09/24

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Subject: Re: Canon F0.95/IR flare?
From: "Jim Bielecki" <jbieleck@northland.lib.mi.us>
Date: Wed, 24 Sep 1997 20:56:36 -0500

 
>    I have just been chatting with an ex aerial photographer
> who has informed me that normally there is a 40-50%
> overlap beteen frames and that only the Center 25% of 
> the image is used to in making a mosiac for a map.
>    This means that a lens for aerial work must be very
> sharp in the center & the rest is expendable since it isn't
> used.  This might or might not account for the alleged
> use of the un-holy Canon lens by our un-holy agency.
>    How about it Irwin & Mark and any ex aerial photogs
> on the LUG;  Do you get flare from the infra red band?
> 
> Marvin 

Hmmm.  Good question.  I do a lot of aerial work with a Rollei 6003
equipped with a 70mm back using Kodak Aerochrome color IR film.  This is
for Natural Resource photography (all Forest Management) which involves
photographing a wide variety of environmental settings (pure forest,
rivers, Lake Superior shoreline, etc.).  I can't ever recall seeing IR
induced flare in any of our transparancies or prints.  This may be due to
the excellent quality of our Zeiss and Schneider optics or to the fact that
only one emulsion layer (out of three) is actually sensitive to infrared
with the Kodak CIR film.

By the way, the 40-50% overlap is to allow stereo viewing. 

Jim Bielecki