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Sodium Vapour Lights & HD

Published : 21st November 2003

I'm shooting some scenes on the Sony F900 for a feature and we have to use a lot of the available Sodium Vapour street light. Does anyone have any suggestions on adjusting the color balance settings in the 900 to make the sodium vapour neutral? I have tried some tests and have had a difficult time removing all of the sodium vapour. White balancing to a white card under the light always gives me a "color temp too low" warning.

Thanks,

Douglas Glover


Sodium vapour lights are not full spectrum. In fact they are incredibly narrow spectrum, outputting frequencies pretty much only in the color that you plainly see. That's why they're so efficient.

So there's no way to balance them, as there is nothing in there to balance with. Reduce that yellowy sodium color and there's nothing else left. If you must shoot under these conditions then you might wish to consider adding other lights with gel packs to emulate the sodium look.

Mitch Gross
NYC DP


Mitch Gross wrote :

class="style9">>Sodium vapour lights are not full spectrum. In fact they are incredibly >narrow spectrum, outputting frequencies pretty much only in the color >that you plainly see.

That's also why they make great darkroom safelights.

Jeff "has a Thomas or two" Kreines


Mitch Gross wrote :

>Sodium vapour lights are not full spectrum. In fact they are incredibly >narrow spectrum, outputting frequencies pretty much only in the color >that you plainly see.

They also make great chroma key lights when you bounce them into a white cove.

Scott Billups - LA


Jeff wrote :

>That's also why they make great darkroom safelights.

Being pedantic, with panchromatic and colour stocks there's really no such thing as a safelight. But sodium vapour, or yellow (580-583nm) LEDs happen to be close to the peak of human photopic (cones) vision (around 550nm) and also at a low point of sensitivity between red and green sensitive emulsion layers. So at least it's safer than other lights.

And totally safe in a HDTV darkroom of course... Just ... not coloured. Totally monochromatic.

Dominic Case
Atlab Australia


class="style9">> And totally safe in a HDTV darkroom of course...

Does HDCAM use the same bath as with the DigiBeta tapes? I understand there's a difference in the thickness between the two tapes so the HDCAM requires less developing time.

Jessica Gallant
Los Angeles based Director of Photography
West Coast Systems Administrator, Cinematography Mailing List
https://cinematography.net


Dominic Case wrote :

class="style9">>Being pedantic, with panchromatic and colour stocks there's really no >such thing as a safelight.

True, true.

My darkroom is monochrome, and I use the light with B&W paper, mostly.

When I have time...

Jeff "stuck at the old drawing board" Kreines


class="style9">>Does HDCAM use the same bath ... My darkroom is monochrome,

Thanks, Jessica & Jeff . . .

I always suspected HD stood for Home Darkroom

Dominic Case
Atlab Australia


I had to do a lot of shooting with Sodium Vapour on a documentary last winter with an MSW-900 (IMX). I white balanced normally, under regular tungsten light...then adjusted the offset on the "A" color balance to about 2400K...that's what seemed to be the best compromise between oversaturated orange, and "nothing left."

This worked for the purposes of the documentary, which involved a lot of riding along with cops at night - the only light inside the car was dashboard and computer monitor light, which read quite blue under a 2400K white balance. The director liked the way the colors immediately separated the police from the "street" - neither was neutral.

Now, if your goal is to make the sodium vapour lights completely neutral... I don't think that's realistic. The best you can hope for is to make it look "less unnatural."

George Hupka
Director/DP
Downstream Pictures
Saskatoon, Canada


Jessica Gallant writes :

>>Does HDCAM use the same bath as with the DigiBeta tapes? I >understand there's a difference in the thickness between the two tapes >so the HDCAM requires less developing time.

Sony's lab manual . . .

see www.sony.com/hdcam/tapestocks/development.pdf

This includes the following fine print : "Before the tape is developed, the anti-abrasion cassette housing must first be dissolved away in a methyl-ethyl-ketone bath. Once the tape spool is free of the housing you can use any kind of bath you want (bar-soap, liquid, flakes, aromatic oils) and the result will be precisely the same in every case, regardless of tape thickness or formulation."

Dan Drasin
Producer/DP
Marin County, CA



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