Sodium vapour white balance

robhooley167

robhooley167

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Rob
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Hello all, been having some difficulty getting a decent White balance for sodium vapour lamps and I was wondering if anyone on TP had any good tips or hints on how to get it sorted. Thanks :)
 
The problem is they do not have a full spectrum of colour so you'll never get a perfect colour.

The best results I've ever managed is with qp cards http://www.qpcard.se/BizPart.aspx?tabId=28 - I've not used the new version but the older one with less colours - so this one must be better....
 
Sodium light is monochromic yellow light (wavelength = 589nm). As such, there is no "color balance" possible. The only thing you could do is to shift the visible yellow to white. Theoretically you would then get a B&W picture, without any colors visible. Objects which absorb yellow light appear dark, and objects reflecting yellow light appear light. Don't expect any blue, green or red color. In the case of a pure sodium lamp you could easier convert to B&W without losing any color information.
In real life, you don't find exclusive sodium light. It's normally mixed with some tungston and/or mercury light. If you now adjust sodium yellow to white, these other light sources will appear extremely blueish.
I'd recommend to shoot RAW and play with color until it looks good. As I said, there is no true compensation possible. That's a matter of physics and it's not camera-dependent!


'Borrowed' from another forum but is very true.
 
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One issue with these is they are not continuous spectrum, so it's harder to filers out the yellow, because instead of a full ranges of colours you have mostly yellow to start with, filter it out and you just get less light unlike say tungsten when you filter out the orange theres other colours left.
One tip is use live view and scroll through the various cilour balances and use the one that looks best as a starting point. Have you tried setting a custom WB? I'm assuming your on jpeg rather than raw.
 
The spectrum is different in high pressure sodium vs low pressure sodium lamps.
Neither is anywhere near ideal as a light source for general photography.
They are classified as HID light sources.
 
I shoot at night a lot and set up a preset on my D300 to adjust the WB to 2500k and shift the hue also. It's not perfect but it gets rid of a lot of the orange without invalidating other colours. You can also turn down the saturation to which takes some of the impact away from the orange tones.
 
AndWhyNot said:
I shoot at night a lot and set up a preset on my D300 to adjust the WB to 2500k and shift the hue also. It's not perfect but it gets rid of a lot of the orange without invalidating other colours.
Click to expand...

Works OK with high-pressure sodium lamps, which have a 'peachy' colour to my eye.

You can also turn down the saturation to which takes some of the impact away from the orange tones.
Click to expand...

Yep.

Or the judicious use of a little flash fill can help and leave the yellows to sort themselves out, depending on the subject


200611_2770 by cybertect, on Flickr
 
Thanks a lot guys, this has been helpful and I will bear what you have said in mind next time I'm near these godawful lamps :)
 
That makes sense, I don't always shoot in raw just due to lack of time and memory card space. But if it makes getting rid of the orange cast a bit easier then I will definitely be tempted to use it more! :)
 
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