As a photographer, I will assume you strive to create as perfect of an image as possible in the camera. If this describes you, then I suggest that you also become the type of photographer that does not reply on post editing to correct lighting and white balance issues. Why not get it right from the start?
I know that a lot of photographers that are just starting out, and those that are more accomplished, do not take a custom white balance before each session and in each varying lighting situation, but you should, and let me tell you why.
Let’s start with AUTO white balance.
When you select the auto white balance mode when you shoot indoors or out, your camera is trying to determine what in the scene is white. Usually, there is nothing in the scene which is true white, and what the heck is true white anyway?
Let’s say you shoot a naked baby on a beige blanket. What in the scene is white?
Let’s say you shoot a pregnant mother’s tummy against a black backdrop. What in the scene is white?
Let’s say you take a toddler outdoors in blue jeans and a red sweater sitting on a green bench with trees in the background. What in the scene is white?
Nothing, nothing, and nothing.
BUT…your camera WILL pick SOMETHING it thinks is white and base the white balance off of that. Not good!
What if the toddler has on a white shirt, and you take a ¾ length image, and the camera bases the white balance off of his shirt, and then you move in for a close up of his face. What is white now?? So now you have multiple colored tones in your session because the camera kept changing the white balance, and the white balance will continue to change as you move in close and back away.
So what about pre-set white balances? Sun, flash, clouds, incandescent, 15 choices of fluorescent, etc.?
Can you pick one that is the exact color temperature of your shooting conditions? Not exactly!
What about choosing the Kelvin temperature? Do you really even know what the Kelvin temperature IS where you are shooting? Do you have a color meter for $800? Do you even need one?
There IS a better alternative; Custom White Balance.
Every camera can take one, and everyone can learn in 5 minutes how to take one, if you just read the manual.
Custom white balance is the process of removing unwanted color casts. Got a subject under a forest of green trees? Custom white balance will clean that up.
Got a baby on the beach underneath of a yellow umbrella? Custom white balance will clean that up.
Your manual may recommend using a white card or white paper to use when taking a custom white balance, but what COLOR white? Warm white? Cool white? Eggshell white? Do you even know what white white is? There are many many shades of white.
What about those expo discs that attach to your lens? What color white is it? Warm? Cool? Exactly my point!
What if your white target is a cool white, and you’re printing on photo paper that is warm white? Now you’re a few shades off.
If you want to use a white paper to take your custom white balance, use the paper you print on!
I recommend doing as your manual says as to how to take a custom white balance but use an 18% gray target such as this for $25. It folds up into your pocket and it HAS no color.
When you take a custom white balance properly, you can eliminate the various colored light in your scene and clean it up, leaving you without a color cast.