How do you determine light balance?

[Kim Welch]

If I am shooting in a room and i want to use the lamps that are in it and natural light from a window how do I know if I need to use filters or not for the film stock. If it is balanced for tungston how do I determine that I have 3200 degrees and not 5500 degrees K? Does anything like this also apply to HD cameras? When I here 5500 degrees K what should I think in terms of getting the best shot and how do I measure this? Is this what the light meter is all about? Can you break it down a little into steps. Like, step one you turn the lights on in the room ... and then what if I want some really black dark corners but I want the shadows in them. I guess I am getting all over the place but to start with i want to get a grip on light and the color and intensity is the starting point, right? so how do i measure these and how do I know how much I need for camera and film stock?

 

[David Mullen ASC]

Well, most cinematographers can see the difference between 5500K and 3200K, if not the average person, even if they can't articulate it. Besides, if it is daylight coming from a window, it's not going to be close to 3200K unless it is an orangey sunset light.

So it's just second nature to know what a tungsten lamp looks like on film in a room with daylight. Now if you can't correct the difference, you might consider balancing halfway between the two and getting a half-orange look from the tungsten practicals and a half-blue look from the windows.

With HD, the cameras have internal filter wheels for different balances, but you can also see the effect of these on a color monitor.

Where it gets harder to figure out is when dealing with partial-spectrum sources like some flos or discharge lamps. You may need a color meter to know for sure; otherwise, you take a guess based on experience or testing.

Nowadays a digital still camera can also be used to show you some of these color differences.