Photography: White Balance

First of all, I am giving you a BIG definition about WHITE BALANCE which I got somewhere on-line. Do not feel dizzy! It makes sense a bit to me.

What is white balance? It all boils down to the concept of color temperature. Color temperature is a way of measuring the quality of a light source. It is based on the ratio of the amount of blue light to the amount of red light, and the green light is ignored. The unit for measuring this ratio is in degree Kelvin (K). A light with higher color temperature (i.e., larger Kelvin value) has “more” blue lights than a light with lower color temperature (i.e., smaller Kelvin value). Thus, a cooler (resp., warmer) light has a higher (resp., lower) color temperature. The following table shows the color temperature of some light sources.

Light Sources Color Temperature in K
Clear Blue Sky 10,000 to 15,000
Overcast Sky 6,000 to 8,000
Noon Sun and Clear Sky 6,500
Sunlight Average 5,400 to 6,000
Electronic Flash 5,400 to 6,000
Household Lighting 2,500 to 3,000
200-watt Bulb 2,980
100-watt Bulb 2,900
75-watt Bulb 2,820
60-watt Bulb 2,800
40-watt Bulb 2,650
Candle Flame 1,200 to 1,500

Note that Kelvin values listed in the table are approximates rather than exact. Moreover, a new light bulb and new flash have higher color temperature than their old and used equivalents, and an electronic flash is designed to have a color temperature comparable to that of average sunlight.

Human brain can quickly adjust to different color temperatures. More precisely, our eyes, with the help from the experience we learned, see a white paper as a white paper no matter it is viewed under strong sunlight or in a room illuminated with incandescent lights. Unfortunately, color films can only correctly record the colors in certain range of color temperatures. Therefore, we have daylight and tungsten films. On the other hand, digital cameras are very different! Digital cameras usually have built-in sensors to measure the current color temperature and use an algorithm to process the image so that the final result may be close to what we see (with our eyes, of course). But, the algorithm(s) being used may not be accurate enough to make every situation correct. Under some difficult situations when the in-camera algorithm is not able to set the color temperature correctly or when some creative and special effects are needed, we can instruct the camera to use a particular color temperature to fulfill our need. This adjustment that makes sure the white color we view directly will also appear white in the image is referred to as white balance.

Setting white balance incorrectly may cause a color shift in the image. For example, suppose the camera is told to use a color temperature of sunlight to take an image of an indoor environment illuminated mainly by incandescent lights. The camera will expect excessive blue light and less red light, and set its algorithm to be more sensitive to the blue light. However, in an environment illuminated with incandescent lights, color temperature is low with excessive red light rather than the blue one. As a result, we shall see a reddish or yellowish image.

On the other hand, suppose we set the camera to a low color temperature (e.g., that of incandescent light) and take a photo under sunlight. Because the white balance is set to incandescent light, the processing algorithm is more sensitive to the red light rather than the blue one. Hence, the resulting image will be bluish as shown in the following images.

“From kenrockwell: Kelvin degrees work backwards from how we expect them to work in photography and common sense. Kelvin degrees are the same as Celsius, except for being 273 degrees apart. (C = K – 273.) This scientific classification refers to how hot something would have to be heated to glow the same color. Imagine your electric heater or range. At lower temperatures it’s more red and gets oranger as it heats up. If it got to 3,200 degrees Kelvin (3,200K) you have the same color as a typical light bulb (and the heating element would explode). If you heated something even more to say 5,500 K it would be brighter and bluer and similar to daylight. Heat the thing up further to say 8,000K and it might be as blue as shade. Yes, the hotter Kelvin looks bluer or cooler, which is why you should ignore this unless you are a scientist.”

Particularly, my babe Nikon D40 and white balance

kenrockwell said “White balance is how you set the color balance, and color is critical. It’s also personal preference. Use whatever looks right to you

All below here I copied from his website, which is correct when I practice with my babe

Auto White Balance. Photo made indoors while cloudy outside. Way too blue and ugly! 99% of people make this shot and never think anything more about it.

AUTO (also called AWB) mode works OK with flash and indoors and outdoors. Usually the images will still be fairly blue in shade and pleasantly warm indoors at night. When the flash is on most cameras automatically switch to flash white balance.

The fun starts when you take it out of AUTO and set it yourself. Here’s what the other settings do:

Tungsten (symbol of a light bulb also called “indoor”): Very, very blue most of the time except indoors at night, for which it looks normal. “Tungsten” is the name of the metal out of which the bulb’s filament is made. Even indoors many people prefer the warmer AUTO setting. TRICK: Set -1 or -2 exposure compensation and use this setting in daylight to simulate night! In Hollywood we call this “day for night.”

Daylight (symbol of a sun): Bluish normal. This is a little bit bluer than I usually prefer. Only use it for shooting test charts in direct sunlight.

Cloudy (symbol of a cloud): I prefer this. It’s a little warmer than the daylight setting and best for most shots outdoors in direct sunlight. Why not the daylight setting? The camera manuals are written by engineers, not artists. The engineers are interested in copying color test charts, not making a good photo. I prefer things on the warmer side.

Flash (symbol of a lighting bolt): Almost identical to cloudy but sometimes redder depending on the camera. Use this the same way. On Nikons like the D70 you usually can set separate fine-tuned adjustments for each setting, so you can set different adjustments under cloudy and flash for quick access. This is optimized for the little on-camera flashes that tend to be blue, thus this setting tends to be warm to compensate. With large studio strobes you probably don’t want to use this, since the images may be too red. Try the Daylight setting to match carefully daylight balanced studio strobes.

Shade (symbol of a house casting a shadow): Very orange. This is perfect for shooting in shade, since shade is so blue. It’s also for shooting when you are under a cloud on a partly cloudy day since most of the light is coming from the blue sky. It’s also for shooting in backlight, again since the subject is lit more by the blue sky instead of the direct sunlight. TIP: Some cameras skip this critical setting. If so, manually set the CUSTOM preset while in shade (also called one-push, Manual and white card and other things depending on manufacturer) and use this setting in place of the missing shade setting. TIP: I often use this mode even in direct sun when I want to make things look warm and inviting. Try it and you’ll probably love it. The SHADE setting is a professional secret for getting great images, pass it on!

Fluorescent (symbol of a long rectangle or Fluorescent tube): Use this if your photos are too green or under Fluorescent, mercury, HMI or metal halide lights as you might find in street lights. It will make other things look a bit purplish. With Nikons the fine-tuning adjustment (+-3) is much stronger in this setting and adjusts from fairly warm to fairly cool. Because of this you may not be able to get the exact color you want under Fluorescent lighting, in which case try AUTO or preset.

Fine Tuning (+3 to -3): Color is critical. The basic settings above get you close, but probably not exactly what you want. These fine adjustments allow you to get the exact amount of coolness or warmth. + is cooler and – is warmer. Nikons allow you to adjust this and remembers your preference for every setting while the Canons often skip this. Without the ability to fine tune these settings I find the Canon Rebel, 300D and 10D cameras not very useful. One can even fine tune Nikon’s AUTO setting. Most photos on my D70 are made in AUTO -3.

Manual, Custom or Preset (sometimes a symbol with a dot and two triangles): This allows you to point the camera at something you want to be neutral and it makes it that way. Read the manual to your camera for specifics. Usually the camera sets itself to what’s in front of you. Some cameras also can set themselves to something in an image shot previously. TRICK: Set it pointed at something colored or through a colored filter and your resulting photos will have a color cast opposite the color to which you set it! Set it on something blue and photos come out yellow, set it on something purple and the photos come out green. Point it at something warm and you get cool and vice versa.

You use this setting if you have some weird light that otherwise you can’t get to look good. I rarely use it, since auto does almost the same thing and makes it much easier.

Some Hints from Kenrockwell

Indoor Sports

When shooting under fluorescent or mercury lighting the color of the light may actually change hundreds of times a second as the AC power cycles. This is no problem with long exposures. On the other hand shooting indoor sports this drove me completely insane until I figured this out. I was shooting at ISO 3,200 and 1/500 of a second. Exposures and color were very different from frame to frame and I had no idea why until I realized that the lights by design were flickering 120 times a second from the 60 Hz power. There is no way around this other than to retrofit the arena with high frequency ballasts for all the lights or otherwise replace or overpower the arena’s lighting. We use high frequency ballasts for our HMI lights in Hollywood so we don’t get beats with the 24FPS film cameras, but its expensive and not done in stadiums. Good luck!

Flash Indoors

What setting do you use for fill flash under tungsten light? If you use AUTO or Flash you’ll get orange backgrounds and normal subjects, and this is pretty good. If you are shooting under fluorescents you’ll get a nasty green background with normal looking subjects, not good.

If you change the white balance to tungsten or Fluorescent the backgrounds will look normal, but now the fill light on the subject will look blue or purple. Not good.

Here’s the trick from Hollywood: you need to gel (filter) the flash to match the ambient light and then set the white balance for that ambient light. Now everything will look normal. You could gel all the ambient light to match the flash instead, but that’s a lot more work since there’s a lot more lights. In Hollywood movies we’ll spend a day gelling all the different kinds of lights and even gel set windows to make outdoors match tungsten. (The funny part is Hollywood is still based on gelling everything to tungsten, since that’s the film we shoot, but almost no lighting is tungsten anymore.)

The best place to buy gel filters, which are just colored sheets of plastic, is your local theatrical stage and lighting supply store. They are a couple of feet on a side and cost a few bucks each. You cut them with scissors and tape them where you need them. Popular brands are Roscoe and Lee. You can get a free sampler from these stores to try out which color works best before you blow a whole few bucks on a full size filter. In the stage world we worry about selecting from among the hundreds of colors they offer. Get the book for cinegels color conversion and correction filters.

I have taken a short course with my teacher, who is a documentary photographer. I am not sure if I remember all what he taught me. So far, I remember some basic concepts, which also my fav parts to play with. I am playing with them slowly for a bit. Then, I will change. After all, I will compare all photos I shot and I will know which style I am down for.

White balance is my first interesting lesson. I really love colors on my photos. I used to use Auto White Balance (AWB) which made my photos so fade. I saw other people’s photos and wondered whether they changed some setting on their cameras or they used Photoshop. Now, I know what is going on with color 😀 No master yet but on the way 😉

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