Tuesday, March 9, 2010

White balance

Have you ever driven down a residential street or looked at an apartment complex at night and noticed how orange or blue the light is coming through some of the windows? Of course, it doesn't look orange or blue when we're in the room. -It's funny how hard it is to see the color of the light that surrounds us, but in order to become better at getting white balance right, that's exactly what we need to do.

To set up our options, I'll list the white balance options you'll find on most cameras:
* Auto
* Tungsten (aka incandescent or indoor)
* Fluorescent
* Flash
* Daylight
* Cloudy
* Shade

"Auto" is often wrong, so for the best accuracy you can set your white balance for the conditions you are in. For example, use:
* Tungsten: for normal "soft white" indoor lighting
* Fluorescent: for the long-tubed fluorescent lighting that you often find in garages and gyms
* Flash: for when you use flash
* Daylight: outside in sunlight
* Cloudy: outside in cloudy conditions
* Shade: outside in the shade

That will get you 90% of the way there -certainly close enough so that only minor tweaks might be needed in software to get your photo to look right.

If you want to understand what it is that the options are doing you'll be able to make better decisions in the field when the setting that matches your conditions isn't giving you what you want. It'll also let you use white balance settings to creatively add a color cast to your photo on purpose.

First, lets go over the color wheel really quick so we can remember what colors are opposites of each other:
* red - green
* orange - blue
* yellow - purple
* green - red
* blue - orange
* purple - yellow

So, when there's a color tint to the light, your white balance setting just adds the opposite color to the photo in an attempt to correct the tint to make white.

* Tungsten: the light is orange-tinted, so the camera corrects for it by adding blue
* Fluorescent: the light is blue/green-tinted, so the camera corrects for it by adding red/orange
* Flash: the light is blue, so the camera corrects for it by adding orange
* Daylight: the light is pure white, so it needs no correcting
* Cloudy: the light is slightly blue, so the camera corrects for it by adding a little orange
* Shade: the light is blue, so the camera corrects for it by adding orange

This means that by taking a photo in daylight with a white balance setting of "shade", your photo will have a very blue tint to it -this can artificially create the look of dusk in a photo taken in the middle of the day.

Of course, if you accidentally left your white balance on "Shade" and shot in the daylight maybe the blue cast wasn't what you're looking for -setting your white balance yourself is slightly risky because if you forget to set it when conditions change, your photos will not turn out as expected.

This subject inevitably leads some to ask -why not leave your white balance on "Auto" and correct for the color cast in software? The answer is ...well, it depends. If you shoot Jpg's, then dramatic color changes can degrade your image, so getting your white balance as close as possible is recommended. If you shoot in RAW, then yes you can adjust it in software with no degradation of the image -as long as you make your white balance adjustments in your RAW file without first converting it to a Jpg (which would defeat the point).