Here are the general steps to establishing a Custom WB. Consult your camera’s instruction manual for details. All you need is a sheet of plain printer paper and your camera.
Position your paper so that it is accurately illuminated by your light source. The angle does matter because it will shift your color temperature. Do not back-light the paper with the light source.
Zoom into the paper so it fills the frame. It doesn’t have to be in focus.
If you can, stop-down your lens to f5.6 or f8 and use the lowest possible ISO combination with that f-stop. The low ISO will reduce color noise which introduces minute errors into WB-ing in both your camera and Photoshop. The higher aperture will reduce vignetting of the lens which also affects the Custom WB.
Expose your image correctly. Because white paper is so reflective, your camera’s meter may tell you to under-expose. Don’t. Snap off a shot and check the image’s histogram. A narrow spike in the center of the histogram means you’ve got it.
Select ‘Custom WB’ from your camera’s main menu. A dialogue screen should show the image of the white paper you shot. Click the ‘Ok’ or ‘Set’ button to import the image’s information.
Set your camera’s WB option to ‘Custom WB’.
In a controlled studio setting, daylight white light bulbs can provide a highly satisfactory alternative to natural light. Using artificial light that is as white as possible will help you achieve truer, more vivid colours.
One trick used by the pros, for example, is to get an assistant to hold a great big reflective sheet of gold-coloured metallic foil to bounce golden light into a scene.
2500-3500K Tungsten household lightbulb
3000-4000K Sunrise/sunset (clear sky)
4000-5000K Fluorescent lighting
5000-5500K Electronic flash
5000-6500K Daylight with sun overhead
6500-8000K Moderately overcast sky
9000-10000K Shade or heavily overcast sky
If your camera has a custom white balance setting, take advantage of it! Select the “custom” option icon and place a white piece of paper or cloth in the scene. Aim the camera so that the entire frame is filled with the white object. Press the “set” or “enter” button on your camera. The camera reads the white object and uses the data from it to set a custom white balance for your composition. Now you can continue to photograph your items.