Understanding White Balance
For many of us who’ve recently switched to digital photography there are new things to learn. One of the more confusing new tidbits of knowledge is just how White Balance works.
When we used film we would select a daylight balanced film type for general photography outdoors or with flash, or a tungsten balanced type for indoor lighting. If the lighting was too cool, we might add a warming filter. Under fluorescent light we’d install a filter that adds blue. So, with film photography we were carrying various filters and film types to adjust to the light’s “Kelvin” color.
With digital photography we are still faced with various lighting types (Kelvin color “temperatures”). However, we can now adjust for any light range without filters by setting the White Balance controls in-camera.
How does White Balance Works?
If we recall our science classes in school, we were taught about the Kelvin temperature range in relation to astronomical objects like stars. Remember that a red giant star is “cool,” while a blue/white star is “hot.” Well, reverse that understanding and you have the White Balance Kelvin system used in most digital cameras today.
With camera white balance we use the Kelvin temperature range in reverse. Why? I haven’t been able to determine that yet; if you know, tell me. However, when you walk out on a cold snowy day and your lips turn blue, do you feel hot like a blue star? No! And when you are out in the setting sun in photography’s magic hour of golden light, does the redness of the light make you feel cool, like a giant red star? No, again!
Just remember we use the Kelvin temperature range in reverse, and that warm colors are reddish while blue colors are cool. This is backwards from what we were taught in school. But, it fits our situation better. Blue seems cool while red seems warm to photographers! Just don’t let your astronomer friends convince you otherwise.
Normally, the White Balance (WB) controls are used to adjust the camera so that whites are truly white, and other colors are accurate under whatever light source you’re shooting. Or you could use the White Balance controls to deliberately introduce color casts into your image for interesting special effects.
Understanding White Balance in a simplified way is simply realizing that light has a range of colors that go from cool to warm. This is called the Kelvin Color Temperature range.
We can adjust our cameras to use the available light in an accurate neutral “balanced” way that matches the actual light source, or allow a color cast to enter the image by unbalancing the settings. We will discuss this from the standpoint of the Nikon D200’s camera controls and how they deal with White Balance.
The Kelvin range, as allowed by the D200, can vary from a very cool 2500K to a very warm 10000K. (See pages 35-44 in your D200 manual for more detail)
In Figure 1 is the same picture adjusted in Photoshop to three white balance settings manually; 3000K, 5000K, and 10000K. Notice how the 3000K image is much bluer or cooler than the 10000K image. The 5000K image is about right for the picture’s actual daylight. The 10000K image is much too warm.
Many of us previously used daylight balanced film and an 81A or Nikon A2 warming filter to warm up our subjects. Or we might add a filter to put some blue in on a foggy day to make the image feel cold and foreboding. We can achieve the same effects with the hard coded white balance settings built-in to the D200.
To achieve the same effect as daylight film and a warming filter, simply select the “Cloudy” white balance setting while shooting in normal daylight (see manual page 35). This sets the D200 to balance at about 6000K which is medium warm, and so makes nice warm-looking images. If you want to really warm the image up, set the controls to “Shade” which sets the camera to 8000K.
On the other hand, if you want to make the image appear cool, try using the Fluorescent (4200K) or Incandescent (3000K) settings in normal daylight.
Remember, the color temperature shifts from “cool” values to “warm” values. The D200 can record your images with any color temperature from 2500K (very cool) to 10000K (very warm), and any major value in between. There's no need to carry different film emulsions to deal with differing light types. The D200 has them all built-in!
Learn to use your White Balance controls to play around with color temperatures, and you will eliminate most of the filters you used to have to carry. The D200 has very easy to use color temperature controls, and a full range of color temperatures available.
There are three separate methods of setting the white balance on the D200.
1. Manual White Balance using the WB button and selecting Options.
2. Measuring the actual ambient light with “PRE” as reflected from a gray or white card.
3. Manual White Balance using the rear LCD Menu and selecting Options.
We’ll consider each of these methods below, since you may prefer to use different methods according to the time you have to shoot, and the color accuracy you want. Most critical photographers will use method number three… the PRE measurement method.
Setting white balance. Method 1. Manual White Balance using the WB Button
Sometimes we might simply want to control the white balance in a totally manual way. This method and the next (1 & 2) are basically the same thing, only one is set using button and dial where the other is set by menu changes.
Each of these methods will allow you to set a particular Kelvin temperature. If you want your image to appear cool, medium, or warm, you can set the appropriate color temperature and take the picture; then look at the image on the LCD.
Here is how to manually choose a White Balance Kelvin color temperature value using the WB button, the sub-command dial, and the top LCD control panel:
1. Press and hold the WB button on the top left of your D200 (see Figure 2).
2. Rotate the rear sub-command dial thumbwheel. Each click of the thumbwheel will change to a new white balance setting such as Auto, 2500K to 10000K, manual Kelvin temperature (K), and PrE in the LCD top control panel.Here we simply select one of the White Balance Options. (See page 35 of the D200 manual, and the table below for more on symbols) These Symbols, Options, and their Kelvin values are as follows:
|3500 to 8000°K
|2500 to 10000°K (Use front dial to choose)
|Direct measured value with grey card
There are a total of nine symbols, as shown in the table above. The eighth selection “K” or Choose Color Temp is a flexible one which allows you to select a Kelvin value manually between 2,500 and 10,000 K. Once you have selected the K symbol by holding down the WB button and rotating the rear sub-command dial, you will then use the front main command dial to select the actual Kelvin temperature you desire.
We will discuss the first and last selections, Auto and PRE in upcoming sections.
Special Note: There is also a method for “fine-tuning” each white balance selection by 10 “mired” clicks, up to 30 mired in either direction. You can modify a basic white balance of, for example, 5000K, from 4970K to 5030K. This works like the Exposure Compensation feature of your D200. (See page 37 of your user’s manual for more information). If you have never heard of “mired” values you can safely ignore this special note. It is for those who are extra critical about fine-tuning the white balance.
Setting the white balance. Method 2. Measuring Actual Ambient Light and Using “PRE” (PrE)
This is the method most will use to set white balance. It is not hard to learn and is very accurate since it’s an actual measurement of the Kelvin temperature of the source light. (See page 40 of the D200 manual) You’ll need a white or gray card to accomplish this measurement.
How to select the PrE white balance measurement method:
Press and hold the WB button.
Rotate the rear command-dial until PrE shows in the lower right of the Control Panel LCD. You’ll also see d-0 in the top left corner next to the Mode letter (A, S, M, P)
Release the WB Button.
Press and hold the WB button again until the PrE starts flashing.
Point the camera at a white or neutral gray card in the light source in which you will be taking pictures. It does not have to focus on the card, just be pointed at it so that it fills the frame.
Press the shutter release fully as if you were photographing the white card. It will fire the shutter, but nothing will appear on the main image viewing LCD.
Check the control panel LCD on top and see if GOOD is flashing.
If you see “No Gd” flashing, instead of “GOOD,” then the operation was NOT successful.
The PrE measurement is very sensitive, since it is using the light coming through the lens to set the white balance. Unless you are measuring in very low light it will virtually always be successful.
Please remember that the flashing GOOD means a successful white balance reading was taken, and your camera is now color balanced for that light source. If you do NOT see a flashing “GOOD,” but instead see a flashing “No Gd” then the operation was unsuccessful and the light may not be bright enough to take an accurate white balance reading.
In step two above I mention “d-0” in the top left corner of the Control Panel LCD during a WB measurement. You can also see it in Figure 3’s first screen shot. This d-0 is one of five nameable memory locations that you can use to store white balance values. Later you can switch between them, or change them, with the WB Button and the two command dials.
You can see these visually in Menu Method # 3, and we’ll discuss them further in the White Balance Tips & Tricks section later.
Here are the screens you’ll see for a successful WB measurement.
FIGURE 3 – Measured PrE, d-0, Good, and No Gd Screens.
Setting the white balance. Method 3. Manual White Balance using the Rear LCD Menu and Selecting Options
Similar to the method #2 above is method #3, the menu selection of the Kelvin range. Instead of using the WB button and sub-command dial, you’ll open up your menus and set the color temperature by selecting from them.
Here are the steps to set your White Balance by menu. Refer to Figure 3 for the different menus:
Normally you will use only the first two screens (see Figure 4) to set one of the “preset” white balance values such as Cloudy, Shade, or Direct Sunlight. If you have previously used the manual “measured” PrE method #2 to set the white balance, you will have a value already in WB memory location d-0. I display the third screen in Figure 4 so that you can see a visual representation of the stored WB values (up to 5 of them, in d-0 through d-4) and so you will know how to use other than d-0 in the future.
This allows you to store White Balance presets in up to five remembered settings and later switch between these at will. This is convenient to use with things like the Shooting Banks and Custom Banks. We’ll mention this again below in the Tips & Tricks section.
White Balance Tips and Tricks
Tips for using a white/gray card: When measuring white balance with a gray or white card keep in mind that your camera does not need to focus on the card. In PrE mode, it will not focus anyway, since it is only trying to read light values, not take a picture. The important thing is to put your lens close enough to the card to prevent it from seeing anything other than the card. Three or four inches (about 100mm) away from the card is about right for most lenses.
Also, be careful that the source light is not casting a shadow from the lens onto the card in a way that lets your lens see some of the shadow. This will make the measurement less accurate. Also, be sure that your source light does not make a glare on the card. That is a little harder to do since the card has a matte surface, but it still can be done. You may want to hold the card at a slight angle to the source light if it is particularly bright and might cause glare.
Finally, when the light is dim, use the white side of the card since it has more reflectivity. This may prevent a “No Gd” reading in low light. The gray card may be more accurate for color balancing, but might be a little dark for a good measurement in dim light. If you are shooting in normal light the gray card is best for balancing. I doubt it makes a lot of difference, however; you might want to experiment in normal light with your camera and see which you prefer.”
Storing White Balance Presets: In the manually measured PrE (method # 2 above) I mention seeing d-0 in the top left corner of the control panel LCD. Also, while setting PRE white balance from the Menus (method # 3 above), the WB memory presets are exposed. Most people will use this one d-0 location. However, if you’d like to store multiple white balance settings and switch between them quickly, just realize that it is adjustable from d-0 to d-4, for a total of 5 white balance memory storage locations. You can even name the locations to something more useful than d-0. (See page 42 of your D200 manual for more detail). Most people will just use d-0 alone.
White Balance Bracketing: You can also do White Balance Bracketing in a way similar to Flash or Exposure Bracketing. Most people do not use this feature, so this article will not cover it in detail. If you want to use bracketing, you must change Custom Setting e5 (see manual page 166) from “AE & Flash” to “WB Bracketing.” This means that flash or exposure bracketing will not work during the time that e5 is set to WB Bracketing. Personally, I prefer to use RAW mode and make minor or major adjustments in the computer postprocessing stage of the image. However, if you would prefer to use WB Bracketing, set e5 and turn to page 43 of your D200 manual to learn how. Just remember to set it back to flash/exposure bracketing when you are done.
Should I use the AUTO White Balance Option Regularly?
Auto White Balance works well in the D200. As the camera’s RGB meter senses colors, it does its best to balance to any white or mid-range grays it can find in the image. However, the color will vary a little on each shot. If you shoot only in Auto WB mode, your camera considers each image a new white balance problem, and solves it without reference to the last image taken. Therefore, there may be variance in the color balance of each image with Auto WB.
If you are concerned with a series of images having the same color settings so that they look similar and require no extra postprocessing, it is best to actually adjust the white balance to one of the preset or measured values. Then, each image taken will have the same color balance.
If I’m at a party, shooting images of friends for small snapshot prints, I’ll often put my camera in Auto White Balance and Program “P” exposure mode. Then, I’ll just take lots of pictures without worrying about a thing. However, if I’m shooting for commercial reasons, or am concerned with maximum image quality, I use a gray or white card and balance my camera to the available light. I only rebalance if the light source changes. Use Auto for when you are not overly concerned about absolutely correct white balance. It’ll be close enough for normal use.
Should I Worry About White Balance if I Shoot in RAW Mode?
The quick answer is no, but maybe not the best answer. When you take a picture using RAW mode (creating .nef files) the sensor image data has no white balance, sharpening, or color saturation information applied to the image. Instead, the information about your camera settings is stored as “markers” along with the raw black & white sensor data. Color information is only applied permanently to the image when you postprocess and save the image in another format, like JPG, TIF, or EPS.
When you open the image in Nikon Capture, or other raw conversion programs, the camera settings are applied to the sensor data in a temporary way so that you can view the image on your computer screen. If you don’t like the color balance or any other setting you used in-camera, you simply change it in the conversion software, and the image looks as if you used the new settings originally when you took the picture.
Does that mean I am not concerned about my white balance settings, since I shoot raw most of the time? No. Remember how the human brain can immediately adjust to an image’s colors and perceive them as normal, even when they are not? That is one of the dangers of not using correct white balance. Since an unbalanced image on-screen is not compared to another correctly balanced image side-by-side, there is a danger that your brain may accept the slightly incorrect camera settings as normal, and your image will be saved with a color cast.
Use your white balance correctly at all times and you’ll make better images for it. You’ll do less post camera work if the white balance is correct in the first place. As RAW shooters, we already have a lot of postprocessing work to do on our images. Why add white balance corrections to the work flow? It's just more work, if you ask me!
Additionally, you might decide to switch to JPEG mode in the middle of a shoot, and if you are not accustomed to using your white balance controls, you will be in trouble. When you shoot JPEGs or TIFFs, your camera will apply the white balance information directly to the image, and save it on your card...permanently. Be safe…always use good white balance technique!
With the simple tips above, and a little study of the manual, you can become a white balance expert with your D200. Learn to use the color temperature settings above to make superior images.
You’ll be able to capture very accurate colors with your camera, or make pictures with color casts reflecting how you feel about the image. Practice a bit, and you'll find it easy to remember how to set your white balance in the field.
Keep on capturing time…
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