Lighting 102: 6.2 - Gelling for Tungsten
Fortunately, tungsten is easier -- and more forgiving.
First of all, when we gel for tungsten, we use an "CTO" gel, which is orange and converts our daylight-balanced flash to tungsten (or incandescent). This means that our little flash has basically been turned into a normal light bulb, as far as light color is concerned.
As you can imagine, this is gonna be pretty orange. But when you are shooting in a tungsten environment, you need to get your light consistent. And CTO'ing the flash makes the flash orange, so your flash and ambient now match. Setting the camera to the tungsten white balance setting (usually denoted by a little "light bulb" symbol) corrects for all of this and brings all of the lights back to daylight.
Except when it doesn't. And there is the rub.
Like fluorescents, tungstens are not always the "correct" color. In fact, a bulb's color can change radically - even moment to moment.
How? By being dimmed.
If you do not believe me, dim down a tungsten light in an otherwise darkened room. Watch as it gets redder and redder. They go almost pure red right before the dim to "off".
TIP: If shooting in a dimmed tungsten room, try to get the lights cranked all the way up. You will get a higher ambient level -- easier for balancing. And you'll get truer tungsten colors -- easier for gelling to balance.
Knowing this, you should now realize that you cannot perfectly balance for all tungsten lights with just a CTO gel. And even if you could balance for everything, you probably would not want to.
First of all, as with our fluorescents, when color converting we can only gel our flashes for something we can reliably correct with white balance settings. And custom white balance is not very useful, because you would have to match the flash's gel pack with the custom color to complete the process.
If you do shoot regularly in, say, the same room with the same whacked-out color, it might be worth it to test a build a gel pack that matches the room light for your flash. Then you could cancel it all out with a custom white balance. But on a daily basis, this is impractical when shooting flash.
Fortunately, flash and tungsten get along pretty well when not perfectly balanced. The main thing is to get your flash correctly CTO'd and balance that at the camera. Then let the ambient tungsten do what it is gonna do.
It frequently will not be perfect, but it will be much better than if you had not gelled at all. And you can also vary the background color effect by how much ambient you choose to include, remembering that the ambient component is controlled with the shutter speed. Balancing down lower with ambient (more stops underexposed) intensifies the color. So bring it up a little so smooth it out.
Long story short, the bad news is that with tungsten, you have a color problem you might not have previously considered. But the good news is that you do not need to be as exacting with tungsten light, so missing it a little is not a tragedy.
CTO and Window Greens explained, we will jump into some fun stuff next -- color key shifting.
NEXT: Assignment: Work That CTO