[Leica] Interesting IR Effect

[hlritter at bex.net (Howard Ritter)]

The dispersion characteristics of most camera optics, which are  
optimized for achromaticity across the visible spectrum only, cause  
IR to focus differently from visible light. (Cf. the fact that many  
lenses have a separate focusing index for use with IR film.)
Blinking of lights per se would not cause their images to be blurred.  
I submit that in your most interesting image, the indistinctness of  
the parts of the image with high IR content is due simply to their  
not having been in focus, as the lens was focused for visible light.

--howard


On Dec 29, 2006, at 12:16 AM, Neal Friedenthal wrote:

> I took this shot of our Christmas tree under ambient room light  
> along with the tree lights.  Because the tree is a real tree it is  
> highly reflective of IR light and apparently the tree lights give  
> off a fairly high
> amount of IR. Also as the tree lights blink the pattern of light  
> from them is constantly changing which may explain the lack of  
> distinct detail in the tree itself, the ornaments, on the other  
> hand, are
> reflecting the ambient constant room lights which are florescent  
> and give off very little IR and they are sharp.  The ornaments  
> appear to be floating on a purple haze.
> http://gallery.leica-users.org/v/NealF/Random/L1021784a.jpg.html
>
>
>
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