Mastering the Nikon COOLPIX A (2014)
Chapter 10. White Balance
Back in the good old days photographers bought special filters or rolls of film to meet the challenges of color casts that come from indoor lighting, overcast days, or special situations.
The COOLPIX A balances itself to the available light with the White balance (WB) controls. Fortunately, the camera’s Auto white balance settings does a great job for general shooting, but discerning photographers learn how to use the White balance controls so they can achieve color consistency in special situations.
How Does White Balance Work?
(User’s Manual, Page 89)
Normally white balance is used to adjust the camera so that whites are truly white and other colors are accurate under whatever light source is present when you are taking pictures. You can also use the white balance controls to deliberately introduce color casts into your images for interesting special effects.
WB color temperatures in photography are backwards from the Kelvin scale we learned in school for star temperatures. Remember that a red giant star is cool, and a blue-white star is hot. The WB color temperatures are backwards because the WB system adds color to make up for a deficit of color in the original light of the subject.
For instance, under a fluorescent light, there is a deficit of blue, which makes the subject appear greenish yellow. When blue is added, the image is balanced to a more normal appearance.
Another example is when you shoot on an overcast day. The cool ambient light could cause the image to look bluish if you don’t adjust it. The white balance control in your camera sees the cool color temperature and adds some red to warm the colors a bit. Normal camera white balance on an overcast day might be about 6000K.
Just remember that photographers use the Kelvin temperature scale in reverse, and red colors are considered warm and blue colors are cool. Even though this is backwards from what we were taught in school, it fits our situation better. To photographers, blue seems cool and red seems warm! Just don’t let your astronomer friends convince you otherwise.
White Balance Fundamentals
Light has a range of colors that go from cool (bluish) to warm (reddish). We can adjust our cameras to use the available light in an accurate and neutral, balanced way that compensates for the actual light source. Or we can allow a color cast to enter the image by unbalancing the settings. In this chapter we will discuss this from the standpoint of the COOLPIX A camera controls and how they are used to deal with WB.
(User’s Manual, Page 91)
You can adjust the WB range of the COOLPIX A from a very cool 2700K to a very warm 8000K. Figure 10.1 shows the same picture adjusted in Photoshop, with the use of software filters, to three WB settings. Notice how the image in the center is about right; the image on the left is cooler (bluish cast), and the image on the right is warmer (reddish cast).
Figure 10.1: One image with three different WB settings: cool, normal, and warm
The same adjustments we used to make with film and filters can now be achieved with the white balance settings built into the COOLPIX A. To achieve the same effect as daylight film and a warming filter, simply select the Cloudy white balance setting when you shoot in normal daylight. This sets the COOLPIX A to balance at about 6000K, which makes nice warm-looking images. If you want to really warm up the image, choose the white balance setting called Shade, which sets the camera to 8000K. Or you could set the white balance to Auto2 (Shooting Menu > White Balance > Auto), which warms up the colors and automatically adjusts for current light sources.
On the other hand, if you want to make the image appear cool or bluish, try using the Fluorescent (4200K) or Incandescent (3000K) settings in normal daylight.
Remember, the color temperature shifts from cool values to warm values. The COOLPIX A can record your images with any color temperature from 2700K (very cool or bluish) to 8000K (very warm or reddish) and several major values in between. There is no need to carry different film emulsions or filters to deal with a range of light colors. The COOLPIX A has easy-to-use color temperature controls and a full range of color temperatures.
Here is a list of the WB settings in the COOLPIX A and their color temperatures, in case you want to add tints to your images:
The White balance settings are represented by symbols in the Quick Menu and the Shooting Menu, under the White balance setting. Here is a list of the symbols, names, and Kelvin WB values:
Often in this chapter I will talk about adjusting white balance in mired increments. Although it is a bit technical, you may want to have a basic understanding of what it means, even if you don’t learn the math.
Mired stands for micro reciprocal degree. It is a unit of measure used to express the differences between color temperature values. It is based on a justnoticeable difference between two light sources and is founded on the difference between the reciprocal of the values’ Kelvin color temperatures (not the temperatures themselves).
The use of mired values dates back to 1932 when Irwin G. Priest invented the method. It is based on the following mathematical formula: M = 1,000,000 / T, where M is the desired mired value and T is the color temperature in degrees Kelvin.
Most of us don’t need to be concerned about understanding mired. Just realize that it means a visual difference between color values.
Manual White Balance Using the Shooting Menu
Manual WB uses the Shooting Menu screens to select the Kelvin color temperature. You choose a specific white balance value from a list of values. The Shooting Menu gives you a greater range of selections and should be used to initially configure, fine-tune, and select a WB.
Afterwards, you can simply choose a WB value from the Quick Menu. Let’s examine both methods.
Figure 10.2: Manual White balance with Shooting Menu screens
Here are the steps to select a White balance setting:
1. Select White balance from the Shooting Menu and scroll to the right (figure 10.2, image 1).
2. Select one of the preset values, such as Flash or Cloudy, and scroll to the right (figure 10.2, image 2).
3. Press the OK button immediately, without moving the black square from its center position in the color box, unless you want to fine-tune the White balance setting (figure 10.2, image 3). WB fine-tuning is discussed later in this chapter.
Normally you’ll use only the first two screens in figure 10.2 to select one of the preset WB values, such as Cloudy, Shade, or Direct sunlight. Then you’ll press the OK button on the final screen, without changing anything.
If you choose to fine-tune any of the color temperature settings after you have selected one of the preset WB values, the color box shown in figure 10.2, image 3, allows you to do so with mired clicks. Each press of the Rotary multi selector in a given direction is equal to 5-mired steps in that direction—up is green (G), down is magenta (M), left is blue (B), and right is amber (A).
If you aren’t familiar with adjusting the preset’s default color temperature, or if you don’t want to change it (most people don’t), simply press the OK button without moving the black square from the center of the color box. If you accidentally move it, simply move it back with the Rotary multi selector until it’s in the middle again, then press the OK button. That will select the WB value without modifying its default value.
Figure 10.3: Seven Fluorescent selections
Note that the Fluorescent selection allows you to choose one of seven different light sources that cover a wide spectrum of Kelvin values. It has an additional screen, as shown in figure 10.3. The extra Fluorescent screen will show up between the screens in figure 10.2, images 2 and 3.
Settings Recommendation: If you shoot pictures that have no relationship to other images, WB is not quite as important, except that it must be accurate for the colors of your subject. Auto WB does a great job for most general photography.
However, if you are shooting in a production environment, such as a studio, and the WB cannot be allowed to vary, it is important that you use one of the preset WB values that matches the color temperature you need for shot-to-shot consistency (e.g., Direct sunlight or Flash).
For absolutely critical applications when the WB must be exact and unvarying, it is important that you learn to use the PRE measurement system to read the ambient light and derive an accurate WB value for your subject.
Selecting a White Balance from the Quick Menu
As previously mentioned, you can select white balance values from both the Shooting Menu and the Quick Menu. We have discussed the Shooting Menu; now let’s briefly examine the Quick Menu method.
You cannot make adjustments, such as fine-tuning, with the Quick Menu, or even select from the individual Fluorescent choices, as you can with the Shooting Menu.
However, it is faster to set the WB from the Quick Menu, so let’s see how.
Figure 10.4: Selecting White balance with the Quick Menu
Use the following steps to select a preset WB value:
1. Press the i button and select White balance (WB) from the Quick Menu (figure 10.4, image 1). Press the OK button to see a choice of WB values.
2. Select one of the preset values, such as Auto1, Flash, or Cloudy (figure 10.4, image 2).
3. Press the OK button to use that WB.
You can select only one Fluorescent value from the Quick Menu—the one that you previously chose in the Shooting Menu > White balance setting. Also, the previous PRE reading (ambient light reading) is available as a choice at the end of the camera’s White balance menu (not shown infigure 10.4). The PRE selection is the one you previously made by reading reflected light from a white or gray card using the Shooting Menu > White balance > Preset manual method. See the upcoming section Measuring Ambient Light Using PRE to learn how to take reflected light readings for WB purposes.
Auto White Balance
Auto White balance works pretty well in the COOLPIX A. As the camera senses colors, it does its best to balance to any white or midrange 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 WB problem and solves it without reference to the last image taken. Therefore, you may see a mild variance in the color balance of each image when you use Auto WB.
Using Auto WB (Auto1 and Auto2)
Auto white balance comes in two flavors: Auto1 and Auto2. The difference is that Auto2 uses warmer colors than Auto1.
For general shooting you need only Auto1, or Auto2 if you prefer warm colors.
Figure 10.5: Auto White balance choices
Here are the steps to select one of the Auto White balance choices:
1. Choose White balance from the Shooting Menu and scroll to the right (figure 10.5, image 1).
2. Select Auto from the menu and scroll to the right (figure 10.5, image 2).
3. Choose Auto1 Normal or Auto2 Keep warm lighting colors, according to your color warmth preference (figure 10.5, image 3). Scroll to the right if you want to fine tune the White balance setting; otherwise, continue with step 4.
4. Press the OK button to lock in the WB setting.
Settings Recommendation: I often use Auto1 white balance on my COOLPIX A. The only time I use anything else is when I am shooting special types of images. For instance, if I am shooting an event with flash and I want consistent image color, I often set the white balance to Flash. Or if I am shooting landscapes under direct sunlight, I often shoot with the Direct sunlight white balance setting. Other than special occasions, Auto white balance works very well for me. Give it a try, along with each of the other settings in their respective environments. This is part of improving your digital photography.
Measuring Ambient Light Using PRE
(User’s Manual, Page 94)
This method allows you to measure ambient light values reflected from a white or gray card to set the WB. It’s not hard to learn and is very accurate since it’s an actual through-the-lens measurement of the source light’s Kelvin temperature reflected from a card.
Figure 10.6: WhiBal card
You’ll need a white or gray card to accomplish this measurement. Figure 10.6 shows the popular WhiBal white balance reference card, which is available at http://michaeltapesdesign.com/whibal.html. The WhiBal card is very convenient because it easily fits in your pocket or camera bag. It comes in many sizes!
Figure 10.7: PRE White balance measurement method
Here’s how to select the PRE White balance measurement method:
1. Select White balance from the Shooting Menu and scroll to the right (figure 10.7, image 1).
2. Choose PRE Preset manual at the bottom of the list. You’ll have to scroll all the way down to find it (figure 10.7, image 2), then scroll to the right.
3. Select Measure to prepare for reading the light from a gray or white card, and press the OK button (figure 10.7, image 3).
4. Choose Yes from the box that says, Overwrite existing preset data?, and press the OK button (figure 10.7, image 4).
5. Follow the instructions on the next screen, which says, Take photo of white or gray object filling frame under lighting for shooting (figure 10.7, image 5). Use a gray or white card in the light that is illuminating the subject, place the camera lens close to the card (about four inches is fine), and press the Shutter-release button. Make sure the lens does not make a shadow that the camera can see. You don’t have to worry about focus because the camera does not try to focus on the card. The COOLPIX A will take a reading of the light on the card, set the camera to the appropriate white balance, and store the white balance reading under PRE for future use (figure 10.7, image 6). You can select this white balance setting any time you want until you overwrite it with a new PRE reading.
The PRE measurement is very sensitive because it uses the light coming through the lens to set the WB. Unless you are measuring an extremely low light level, it will virtually always be successful.
Next, let’s examine how to get a WB value from an existing image.
Using the WB from a Previously Captured Image
You can also select a white balance setting from an image you have already successfully taken. The WB value from the previous image can be applied to pictures you are about to take.
Figure 10.8: Using White balance from a previously taken image
Here are the steps to recover the White balance setting from an image stored on your memory card:
1. Select White balance from the Shooting Menu and scroll to the right (figure 10.8, image 1).
2. Choose PRE Preset manual at the bottom of the list. You’ll have to scroll all the way down to find it (figure 10.8, image 2), then scroll to the right.
3. Select Use photo and scroll to the right (figure 10.8, image 3).
4. If you have previously done these steps, the image you used will be displayed (figure 10.8, image 4). You can use it again by choosing This image and skipping steps 5 and 6. Otherwise, if you’ve never used this function before, you will see a thumbnail-sized white rectangle instead of a thumbnail picture. Or, if you prefer to use a different image as the WB source, choose Select image and scroll to the right.
5. You will see a list of folders that contain images. Select a folder and scroll to the right (figure 10.8, image 5). My camera has only one folder, which is named NIKON.
6. You will see six thumbnail images, but you can scroll around in all the images in the folder with the Rotary multi selector. Choose the image that was shot with the WB you want to use and press the OK button. The WB value is now set in the camera. A screen similar to the one in figure 10.8, image 4, will appear, with a thumbnail of the newly selected image. This image will be highlighted. Press the OK button to finish the process.
Now, let’s see how to fine-tune a WB value.
Fine-Tuning White Balance
(User’s Manual, Page 92)
If you want to fine-tune a white balance to have more of a certain color, you can do it with the Shooting Menu WB settings.
If you want to fine-tune a previously saved White balance value, you can use the Set function. The value in any of the d-0 through d-4 memory locations can be manually changed. You can move the color balance toward green (G), amber (A), magenta (M), or blue (B), or you can move it toward intermediate combinations of those colors.
Figure 10.9: Fine-tuning White balance with Shooting Menu screens
Here are the steps to fine-tune a White balance setting using the Shooting Menu screens:
1. Select White balance from the Shooting Menu and scroll to the right (figure 10.9, image 1).
2. Choose one of the White balance options from the menu. I chose Fluorescent. If you choose any other option besides Auto1 or Fluorescent, there will be one less screen in the series shown in figure 10.9. The intermediate screen shown in image 3 does not exist for the other WB options. After you have chosen an option, scroll to the right (figure 10.9, image 2 or 3).
3. Use the Rotary multi selector to adjust the color balance by moving the black square from the middle of the color box toward any direction (figure 10.9, images 4 and 5). If you change your mind, return the black square to the center of the color box. You’ll see the mired values change on the right side next to A–B and G–M. Each increment (click) of the Rotary multi selector is equal to about 5-mired steps. Therefore, if A–B is set to A3, it means an additional 15-mired of amber has been applied to the current WB; similarly, if G–M is set to G3, it means an additional 15-mired of green has been applied to the current WB.
4. Press the OK button to save your adjustments to the current White balance option (figure 10.9, image 6). You will see that a small asterisk is now displayed next to the WB option, indicating that it is a modified WB option. Return the black square to the middle of the color box and press the OK button to return the WB option to its default setting. The asterisk will then disappear.
Should I Worry about White Balance if I Shoot in RAW Mode?
The quick answer is no, but that may not be the best answer. When you take a picture using NEF (RAW) mode, there is no white balance, sharpening, or color saturation information applied to the image data. Instead, the information about your camera settings is stored as markers along with the RAW black-and-white brightness data. Color information is applied permanently to the image when you post-process and save the image into another format, such as JPEG, TIFF, PNG, GIF, or EPS.
When you open the image in Nikon Capture NX 2, or another RAW conversion program, the camera settings are applied to the data in a temporary way so 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 can simply change it in the conversion software, and the image looks as if you used the new setting when you took the picture.
Does that mean I am not concerned about my WB settings since I shoot RAW most of the time? No. The human brain can quickly adjust to the colors in an image and perceive them as normal, even when they are not. This is one of the dangers of not using the correct WB. Since an unbalanced image on your computer screen is not compared to another correctly balanced image side by side, there is some danger that your brain may accept the incorrect camera setting as normal, and your image will be converted to the new file format with a permanent color cast.
As a rule of thumb, if you use WB correctly at all times, you’ll consistently produce better images. You’ll do less post-processing if the WB is correct in the first place. As RAW shooters, we already have a lot of post-processing work to do. Why add WB corrections to the workflow?
Additionally, you might decide to switch to JPEG mode in the middle of a shoot, and if you are not accustomed to using the WB controls, you’ll be in trouble. When you shoot JPEGs, your camera applies the WB information directly to the image and saves it on your memory card—permanently. Be safe; always use good WB technique!
White Balance Tips and Tricks
When you measure the WB 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 because 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 75mm to 100mm) away from the card is about right for most lenses.
Be careful that the lens does not cast a shadow that your camera can see onto the card. If your camera sees a shadow, the measurement will be less accurate. Also, be sure that your source light does not produce glare on the card. This problem is not common since most cards have a matte surface, but it can happen. You may want to hold the card at a slight angle to the source light if the light is particularly bright and might cause glare.
Finally, when the light is dim, use the white side of the card because it has more reflectivity. This may prevent a bad reading in low light. The gray side of the card may be more accurate for color balancing, but it 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. You might want to experiment in normal light to see which you prefer.
If your camera cannot take an accurate PRE reading, for any reason, it will warn you with an error message on the Live view screen that says, Unable to measure preset white balance. Please try again. If you see this, you may need to increase the amount of light. It will have to be extremely dark for this error to occur, though, because the camera is quite sensitive in low light.
With these simple tips and some practice, you can become a COOLPIX A WB expert. Starting on page 89 of your user’s manual you’ll find extensive WB information—in case you want another perspective on Nikon WB.
Learn to use the color temperature features of your camera to make superior images. You’ll be able to capture very accurate colors or make pictures with color casts to reflect how you feel about the image. Practice a bit, and you’ll find it easy to remember how to set your WB in the field.
Now, let’s turn our attention to the video subsystem in the COOLPIX A. The camera is ready to make high-quality 1080p and 720p videos. Your tiny COOLPIX A is a powerful little video camera.
Let’s make some movies!