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Making tungsten practicals appear blue via WB as a last resort?


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Working on a student music video. It's at night in a perfect car park location that is being lit by various lampposts. It is a similar location to this Casey Neistat Samsung ad (I coloured corrected the screen-grab to appear blue). 

I want the lampposts to give a cool blue look, however, the trouble is that the location I have, the lampposts are tungsten. 

As they are in the shot, I am unable to gel the lampposts or anything like that. So I am wondering if it is a ludicrous idea to make the tungsten lampposts appear cool blue by manipulating the white balance in-camera? 

I also want a 'white light', neutral key-light on the subject and so I'd just make the key light the same kelvin as whatever the camera will be when adjusted to make the tungsten lamposts appear bluer (to taste). 

Is this a terrible idea and I just need to scrap the location and find a car-park with cooler daylight lampposts? or could this potentially work?
Would love to hear peoples thoughts!
Thanks!

 

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Edited by imran qureshi
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It can be done. You'll need to WB to about 2000k, maybe even lower. This will cause a big imbalance in the gain applied to the RGB channels in your camera, so it probably won't be correctable without introducing a lot of noise if you change your mind.

Also, tungsten streetlights are extremely rare in the UK. Almost all were replaced by sodium vapor many years ago, and more recently by LED. Are you sure that you've got that right? It might make a difference.

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1 minute ago, Stuart Brereton said:

It can be done. You'll need to WB to about 2000k, maybe even lower. This will cause a big imbalance in the gain applied to the RGB channels in your camera, so it probably won't be correctable without introducing a lot of noise if you change your mind.

Also, tungsten streetlights are extremely rare in the UK. Almost all were replaced by sodium vapor many years ago, and more recently by LED. Are you sure that you've got that right? It might make a difference.

Yeah sorry, it was a bit of a generalisation to say it was tungsten, it is probably sodium vapor. Here is a blury phone picture of the actual location.  I was going to go to the location with my camera and figure out the actual kelvin of the lights by adjusting the white balance in camera until I get a neutral white light.0.jpeg.196a9c9da7bb748cd8e5f4d59082c6a3.jpeg

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1 hour ago, imran qureshi said:

Yeah sorry, it was a bit of a generalisation to say it was tungsten, it is probably sodium vapor. 

Remember that sodium vapor is a monochromatic source (or as near as makes no difference). Those lamps only emit light in a very narrow range of frequencies in the yellow/orange spectrum, and are far warmer than tungsten. You'll be trying to add gain to the blue channel, but there is no blue light in sodium vapor lamps. That will make white balancing it to look cold much more difficult, and will introduce a lot of noise into the blue channel.

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20 minutes ago, Stuart Brereton said:

Remember that sodium vapor is a monochromatic source (or as near as makes no difference). Those lamps only emit light in a very narrow range of frequencies in the yellow/orange spectrum, and are far warmer than tungsten. You'll be trying to add gain to the blue channel, but there is no blue light in sodium vapor lamps. That will make white balancing it to look cold much more difficult, and will introduce a lot of noise into the blue channel.

Understood, so do you think i'm better off scraping the location and try to scout a location with white LEDS? thanks!

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Try grading a monochromic image of the scene blue to see how that looks.  In the past, they've shot day for night seascape scenes in B & W film and then printed them blue,.

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As Brian says you can push it to black and white and then just tint it in post, though you'll then get everything being blue. Then again, that's more or less what you've got in the example image you showed.

As to white balance tricks, try it. Balance with a piece of CTO gel over the camera, remove the gel, and you should have a cold-looking scene. Test, and look at it carefully, though, on a big, full-resolution monitor in comfort when you get home, to make sure you aren't pushing the noise up to a place you're not happy with.

Street lights like those are a shocking pain; there's often not much you can do with them. If it's really not what you're after and you can't get a result you like with in-camera or post tricks, as you say, scrap it and find somewhere else.

LED street lighting often has a cool, cyanotic look if that's what you're after.

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Following up on Brian’s idea, I once shot a monochromatic blue night scene using ungelled tungsten lights. In Resolve instead of using the color wheels i used the color mixer tool to remap all luminance info to the blue channel. This induced no noise contrary to other methods. The key for this to work is was that the scene has got to be monochrome.

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Yeah something like this would need tests to make sure you can pull off the effect. Those sodiums are so warm, even putting a CTB over the lens wouldn't make them as cold as your example. And a CTB cuts almost 1 2/3 stops.

It could be a combination of blue lens filter with white balance.

It could be color shifted in post.

My stab at it would be to avoid the white balance (because as Stuart said, it will be noisy with that much blue gain in camera), and instead shoot at 5500k and daylight sources for the subject, then in post, select the sodium color and shift from there. That should keep the subject and BG colors individually adjustable in post. It would still need a test to be sure.

 

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If you can’t find a location with blue LED street lamps, I would do it with in-camera white balance and color grading. 

Here’s a quick and dirty grade on my phone with Lightroom Mobile: 

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