Archived posting to the Leica Users Group, 2003/12/07

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Subject: Re: [Leica] IR Infrared Filter
From: John Collier <jbcollier@shaw.ca>
Date: Sun, 07 Dec 2003 18:31:56 -0700
References: <26C37BB4-290F-11D8-A88E-000A9578C446@ncable.net.au> <075501c3bd20$6a4696c0$0200a8c0@Desk>

Yes Leica and others made opaque IR filters but not ones that corrected 
the focus because that is too lens specific. The standard E39 filter 
fits a wide variety of lenses which would all require a different 
correction factor depending on the focal length and even which version 
of the optical design.

John Collier


On Dec 7, 2003, at 5:15 PM, robertmeier@usjet.net wrote:

> Does anyone know if Leica ever made an infrared filter like the one 
> Rollei
> made?   The Rollei filter is distinguished for two things:  it is all 
> but
> opague, only passing the infrared wavelengths, and it is slightly 
> ground to
> compensate for the different focus point needed for infrared light, so 
> no
> compensation is needed on the focus setting.   Since with a Rollei, 
> like a
> Leica, you don't view through the taking lens (and the filter), the 
> opague
> filter works all right.  I would love to use such a filter on my 
> Summircon
> 50, and I might have to tape my Rollei Bayonet II filter on to it (the
> diameters are just about identical).

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In reply to: Message from Alastair Firkin <firkin@ncable.net.au> (Re: [Leica] PAW 49 dlridings)
Message from robertmeier@usjet.net (Re: [Leica] IR Infrared Filter)