One of the challenges photographers face is understanding “white balance” — basically, rendering color correctly under various types of light. There are many good descriptions out there of this. Here’s Ken Rockwell, for instance:
Different kinds of light require different adjustments to give a good picture. If we consider full daylight as “normal,” then indoor incandescent screw-in light bulbs look orange by comparison and candle light looks almost red. Likewise, blue sky without the sun is very blue although when you’re in the shade everything looks OK to you and I. If you make a photo in the shade the picture comes out way too blue or cool looking.
This is because different kinds of light have different amounts of red, green and blue.
And that’s just dealing with the world as you find it. Start adding light deliberately, and things get complicated quickly.
For instance: I lit this wig head (I guess I’ll have to give her a name soon…) with two 100 watt household light bulbs screwed into clamplights with 8″ reflectors. Then I shot the image using the “auto wb” setting.
The camera read this correctly. The color in “her” gold, glittery New Year’s hat is bang on, the styrofoam is still a nice bright white, and the shadows are neutral grays. So even though those bulbs cast an orange-y tint, cameras can compensate and deliver accurate colors. (Yes, I could have directly set the white balance, but that would have defeated my purpose in this exercise…)
But while all’s well with the color, the photo itself is not. The title of the book is deep in shadows, and the whole reason I included it in this shot was because I thought the title was appropriate for what I was doing.
Since the book cover was not receiving any light at all from the clamp lights, I fired the camera’s on-board flash (at a radically reduced power, since I was very close to it). Look what happened to the color:
Ack! What happened to my nice white styrofoam?
The problem here is that I introduced a totally different type of light to the equation. Although the clamp lights are using ordinary household bulbs (casting an incandescent light), my strobe fires a blue-ish light (basically a full daylight color)… and the camera compensated with an orange tint.
Mixing the light sources confounded the camera’s ability to read the situation. This might have still been okay if I’d been firing the strobe at much higher power (so it was the primary light source), but since it was only lighting the foreground, my wig head’s a mess.
So…. could I have set the camera’s white balance to handle this mixed light situation?
Since this is exactly the type of issue that drove me to take a lighting course this month, I took the question straight to the instructor. And although he gave me the answer (more than one answer, actually), I’m going to hold off on sharing it. Instead, I wonder how you think this could have been handled.
What do you think? How could I have fired the small strobe in an incandescent light setting while maintaining the correct color balance?
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