[LRflex] Re: Was: Concentration; Now: Colour of light. (HELP!)

David, Eteinne, & Aram,

This may be ³politically incorrect,²  but if the ³ low pressure sodium
(natrium), discharge lamps² make the room appear yellow to the eye, then
leave the photo alone. It is correct as it stands, as that is the way it is
seen by visitors.

Besides, I like it that way! Stunning!

All the best,

Bill


On 7/16/08 10:24 AM, "David Young" <dsy@xxxxxxxxxxxxxxx> wrote:

> At 16/07/2008, you wrote:
>> Hi  David !
>>  
>> The yellow lights you refer to are, in my modest opinion, low pressure sodium
>> (natrium), discharge lamps.
>>  
>> The light emitted is monochromatic i.e. all the luminous energy is emitted at
>> a single wavelength of approx. 5900 Angström (or in a very, very narrow
>> bandwith centered on that wavelength).
>>  
>> The main advantage of this light source is its very high efficiency, up to
>> 190 lumens per watt (to be compared to 20 lumens/watt for quartz halogen
>> filament lamps).
>>  
>> Its main drawback is that its use is limited to places where colour
>> recognition is not important (roads, tunnels ...). E.g. a red object will
>> appear black or very dark brown under this light source.
>>  
>> All the best !
>>  
>> Etienne
> 
> 
> Eteinne & Aram:
> 
> Thanks for the pointer as to the type of light.  I had assumed that it was LP
> Sodium, but was not aware of the severely limited spectrum.
> 
> Years ago, Victoria, BC, was one of the first places to use these lamps for
> street lighting.  They were encouraged to do so by the Dominion Astrophysical
> Observatory, there, which was suffering tremendous light pollution, as the
> city had overgrown the observatory.   Since they do a lot of spectrography, I
> now see why these lamps were a huge improvement to the light pollution
> problem!
> 
> Still, it does not help correct the colours in my photo ... although I am now
> beginning to think this is not possible.
> 
> Thanks, both, for your help.
> 
> Cheers!
> 
> ---
> 
> David Young,     
> Logan Lake, CANADA
> 
> Limited Edition Prints at: www.furnfeather.net <http://www.furnfeather.net/>
> Personal Web-site at: www.main.furnfeather.net
> <http://www.main.furnfeather.net/>
> Stock Photography at: http://tinyurl.com/2amll4
> 
>

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