Archived posting to the
Leica Users Group, 2006/01/18
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Subject: [Leica] Leica IR filter
From: robertmeier at usjet.net (Robert Meier)
Date: Wed Jan 18 08:24:39 2006
References: <6.1.0.6.2.20060114232020.0ab9def8@192.168.100.42><43CC7ED1.4070009@planet.nl><057101c61b29$56c02580$0400a8c0@robertbxucevjs><938A764A-505B-4822-B2BB-DD3735B8FA9D@shaw.ca><05e601c61b76$b178c250$0400a8c0@robertbxucevjs><26d1eb9a0601171107j48ed8daaxf44723ccf2f5ec48@mail.gmail.com><063601c61ba1$371167d0$0400a8c0@robertbxucevjs> <p06230909bff303968a9a@[10.4.1.157]><069201c61bd1$042e5d20$0400a8c0@robertbxucevjs> <p06230911bff3528209ee@[10.4.1.157]>
Henning,
Thank you for your explanation. So, the compensation needed would be for
the wavelengths beyond 900nm. Interesting.
Bob
> >The filter controls what wavelengths get through, of course. The filter
> >therefore can be ground to compensate the focus point for those
> >wavelengths. What the film records should not be a factor, since it can
> >only record what gets through to it.
>>
>>Bob
>>
>
> All filters let through a large range of wavelengths; most IR filters pass
> wavelengths well beyond 900nm while few films are sensitive in that
> region. Therefore compensation differences due to the emulsion matter.
>
> Since the main issue for the IR filters is the low cutoff to match it to
> subject matter, film sensitivity and thus exposure time, the upper end is
> usually left free to take advantage of whatever sensitivity the film may
> have.
>
> --
> * Henning J. Wulff
> /|\ Wulff Photography & Design
> /###\ mailto:henningw@archiphoto.com
> |[ ]| http://www.archiphoto.com
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>
Replies:
Reply from henningw at archiphoto.com (Henning Wulff) ([Leica] Leica IR filter)
In reply to:
Message from richard-lists at imagecraft.com (Richard) ([Leica] any reasons NOT to get a M Classic bag...)
Message from nathan.wajsman at planet.nl (Nathan Wajsman) ([Leica] any reasons NOT to get a M Classic bag...)
Message from robertmeier at usjet.net (Robert Meier) ([Leica] Leica IR filter)
Message from jbcollier at shaw.ca (John Collier) ([Leica] Leica IR filter)
Message from robertmeier at usjet.net (Robert Meier) ([Leica] Leica IR filter)
Message from huntmc2 at gmail.com (Marshall Hunt) ([Leica] Leica IR filter)
Message from robertmeier at usjet.net (Robert Meier) ([Leica] Leica IR filter)
Message from henningw at archiphoto.com (Henning Wulff) ([Leica] Leica IR filter)
Message from robertmeier at usjet.net (Robert Meier) ([Leica] Leica IR filter)
Message from henningw at archiphoto.com (Henning Wulff) ([Leica] Leica IR filter)