[LRflex] Re: Was: Concentration; Now: Colour of light. (HELP!)
- From: William Abbott <m.tahoe@xxxxxxxxxxxxx>
- To: <leicareflex@xxxxxxxxxxxxx>
- Date: Wed, 16 Jul 2008 10:54:37 -0700
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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