Official terminology : On professional-level cameras, it can mean the white balance operation as described below (which is actually quite manual). This is because in professional situations, a "manual white balance" can mean altering colours using specialised vision processing equipment. If your camera has a filter wheel (or if you use add-on filters), make sure you are using the correct filter for the lighting conditions. Point your camera to a pure white subject, so that most of what you're seeing in the viewfinder is white. The subject should be fairly matte therefore non-reflective. Set your exposure and focus. Activate the white balance by pressing the button or throwing the switch. The camera may take a few seconds to complete the operation, after which you should get a message (or icon) in the viewfinder. Hopefully this will be telling you that the white balance has succeeded - in this case, the camera will retain it's current colour balance until an...