White balance is the tool to help get the colors in your images as accurate as possible. White balance setting is based on the color temperature while shooting and those color temperatures are measured in a Kelvin scale. Higher the temperature, more blue light exists and lowers the temperature, more red light exists. You can take an example of fire; lower temperature fire produces red flame whereas higher temperature fire produces blue flame. As a photographer it is important to know that any light below 4000k starts to appear as a red light and any light above 7000k or so starts appearing bluish. In photography, you have to understand that warmer light means red or yellow and cooler light means blue light. You have to judge the environment and lighting condition where you are shooting and adjust the white balance accordingly to get the nice and pleasant effects to your photographs.
Nikon DSLRs come with the pretty standard predefined settings like Auto, Incandescent, Fluorescent, Direct Sunlight, Flash, Cloudy, Shade, Color temp and preset manual. Auto White Balance (AWB) works pretty well most of the time but sometime you need to change your settings to different available options. It's pretty easy to change the white balance option to one of the predefined settings. You just have to navigate through the white balance option from the menu button on the back of the camera (button location depends on your camera model) and select whatever value you want to set. If you are shooting under tungsten light bulb, you may want to change the white balance to Incandescent and if you are shooting outside, you may want to choose the direct sunlight and so on.
If you want to set the custom White balance rather than what is already provided with your camera, you have an option in Nikon camera and it's called Preset Manual. If you scroll all the way down to the white balance setting, you will see the last option as a preset manual denoted by 'PRE'. If you have not setup custom white balance using the preset manual before, you will see bunch of blank memory slot denoted by d-0, d-1, and d-2 and so on. These are camera's memory slot to store the data from which it reads the white balance data if you choose to select the preset manual white balance instead of other predefined values we discussed earlier. Now let’s discuss how to set the custom white balance.
How to set the Custom White balance using Preset Manual?
1. Set your camera into P, S, A or M mode.
2. Press and hold the WB (White Balance) button while rotating the rear command dial to select 'PRE' in the control panel and then release the WB button. When white balance is in 'PRE' mode, you can use front command dial to change the memory slot from d-0 to d-1, d-2 or others if you want.
3. Press and hold the WB button for few seconds again and you will see 'PRE' starts blinking on the top LCD screen.
4. While 'PRE' is blinking, take a shot of white or grey index card (Note: 'PRE' blinks about 10 seconds and you have to take a picture while it is blinking).
5. If the camera was successful to get the white balance data from your photographs, it will display 'Good' on the LCD screen and if not, it will display 'no Gd' and you have to try again with the proper exposure.
6. After you complete the process and set your custom white balance, your camera will take the reference of that image while applying the white balance to your shots unless you have set your white balance to some other settings than PRE.