Archived posting to the Leica Users Group, 2006/12/21

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Subject: [Leica] IMG: Another Comparison
From: davison_m at msn.com (MARK DAVISON)
Date: Thu Dec 21 05:27:05 2006

Tina,

Incandescent light is particularly rich in infra-red.

Remember also that the part of the image due to infra-red light will not be 
in focus.  That might account for part of the blurring of the flame image.

I would bet that the flag in your picture was made out of synthetic fabric.  
Synthetics are notorious for their high IR reflectivity.

My opinion is that you cannot use the M8 to photograph indoor events in 
color which are lit by IR rich sources if there are synthetic fabrics 
present.

Please note that changing WB after the fact cannot fix the IR problems--the 
IR contamination shifts the colors of objects differently, depending on how 
much they reflect IR. Synthetic black goes to magenta.  Synthetic green goes 
to gray, and so forth.

Mark Davison


>From: Tina Manley <images@InfoAve.Net>
>Reply-To: Leica Users Group <lug@leica-users.org>
>To: Leica Users Group <lug@leica-users.org>
>Subject: RE: [Leica] IMG:  Another Comparison
>Date: Wed, 20 Dec 2006 13:37:25 -0500
>
>At 11:04 AM 12/20/2006, you wrote:
>>Given that candles are a strong source of IR, I would guess that this is 
>>almost entirely an IR problem.
>
>
>I hadn't thought of that angle.  Thanks, Brian.  I guess I'll avoid taking 
>photos of candles with my M8 until I get my IR filters.  What else would be 
>a strong source of IR that I might have to avoid?
>
>Tina
>
>Tina Manley, ASMP, NPPA
>http://www.tinamanley.com
>
>
>_______________________________________________
>Leica Users Group.
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Replies: Reply from mark at rabinergroup.com (Mark Rabiner) ([Leica] IMG: Another Comparison)
Reply from images at InfoAve.Net (Tina Manley) ([Leica] IMG: Another Comparison)
In reply to: Message from images at InfoAve.Net (Tina Manley) ([Leica] IMG: Another Comparison)