Archived posting to the Leica Users Group, 2007/10/12

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Subject: [Leica] 28mm Summicron IR problem
From: cummer at netvigator.com (Howard Cummer)
Date: Fri Oct 12 18:38:00 2007
References: <200710130106.l9D15Ram055431@server1.waverley.reid.org>

Dear Len,
How about the 28mm setting on the TriElmar? I have shot many IR  
photos using this lens and did not notice the hotspot phenomena you  
experienced with the Summicron.
Cheers
Howard.

On 13 Oct 2007, at 9:06 AM, lug-request@leica-users.org wrote:

> Date: Fri, 12 Oct 2007 20:51:42 -0400
> From: Leonard Taupier <len-1@comcast.net>
> Subject: Re: [Leica] George: 28mm Summicron IR problem
> To: Leica Users Group <lug@leica-users.org>
>
> In addition to the sensitivity of the sensor the quality of digtal
> infrared depends on the characteristic of the lens.
>
> For example, the Canon EF-S 18-55mm f/3.5-5.6 typically produces a
> pronounced hot spot as can be seen in the sample picture to the left.
> The hot spot is a a result of internal reflections within the lens
> produced by the lens' coatings. Some types of coating are not
> transparent to near-infrared wavelengths.
>
> The above was taken from a web site dedicated to Infra Red digital
> photography. Quite a few lenses are listed which produce these hot
> spots. The author did not include Leica lenses in the recommended or
> hot spot producing lists.
>
> Len
>


Replies: Reply from len-1 at comcast.net (Leonard Taupier) ([Leica] 28mm Summicron IR problem)