Digital White Balance

This tip assumes:

1. You are shooting pictures with a digital camera
2. Your digital camera, lets you tell it what general light you are shooting under (ie, daylight, incadescent light, flash, and others)
3. Your digital camera lets you create "custom white balances." (The first tips don't require this, but the big tips do.)
4. You must be able to turn off the white balance.

So why do you need to do a white balance on a digital camera - can't the camera figure it out on its own? Isn't that why I paid several thousand dollars for a great professional digital camera?

Well, first of all. When I am shooting in constantly changing light, when I am doing "grab" shots, spontaneous, spur of the moment, shots, yes the digital camera's white balance is often excellent, especially if the subject is, on average, well, average.

But if you take a picture of a red sunset, or a girl dressed in a long red dress driving a red car - the camera is going to say "oh, look at all that red, this picture must be taken with incadescent light bulbs", or a green sailboat sitting on a green lawn with green trees, the camera might decide that, with all that green, the picture was taken under flourescent lights!

Can you just pick the "daylight" setting and force it to use daylight? Well, yes and no. You see, daylight changes through the day (see my tip on My Favorite Light for discussion of different types of daylight.) Sufficee it to say that your camera's "daylight" setting will be preset to something like "noon" (very blue) or "10:00 and 2:00 light" (not quite as blue). If your camera is more flexible, it might have multiple daylight settings, and yes, that is better yet! But if you want the ultimate quality shots, it often is not good enough, especially if you are shooting "TIF" (TIFF) or "JPEG".

Technical aside: I should probably make this a full blown tip, but for now: JPEG and TIFF are 8 bit color formats. This means they can cover nearly the full range of color your eye can see, and each different color should be the smallest difference your eye can see. But it just barely is that good. If you take a properly exposed picture and don't want to change its dynamic range or fiddle with it, then everything is fine. But since 8 bits is "just" good enough, if you need to change the exposure, need to change the contrast, need to correct a color/colour cast, need to make any other similar changes, it frequently isn't good enough anymore. If on the other hand you take a RAW file with, commonly, 12 bits, that has 16 times as much "differences" as your eye can see. NOW, when you adjust exposure, contrast, color cast etc.., and then convert it to an 8bit format like TIFF or JPEG the image frequently is still better than you can see, nothing is messed up from your eyes perspective. In general, if you software can handle your camera's RAW file format, you should shoot JPEG or RAW - never TIFF. If speed is what you need or you are sure about your settings or file size is the biggest issue, shoot JPEG. Otherwise, shoot RAW. (I switch back and forth depending on need.) If you shoot RAW, do all your color editing, contrast, exposure changes first, then save the file to TIFF for other retouching like soft focus.

So. What if you want to have the easiest time in your computer getting color correct? The technique is called a "custom white balance". This is where you teach the camera the characteristics of the current light so that you can make the proper conversion. When would you use this?

• A times of the day different from the pre-sets of your camera
• When the presets just don't work (there is a way to test - coming up)
• When you want to have your camera match your flash (the flash on the camera, or your studio flashes.)

As you will see in a moment, this technique is not appropriate for the "grab" shot.

First, here are the steps, then I'll talk about them in more detail:

Step 1: Turn off white balance on your camera. Tell it to give you the file the way it saw it.
Step 2 Option a) Shoot the whitest object you can find.
Step 2 Option b) Shoot a Kodak Gray card (or other known "18% gray" surface)
Step 3: Load the file into your computer
Step 4: Check the RGB values. If you picked option 1, they must AVERAGE in the range of 240 to 245. If you picked option 2, they must AVERAGE in the range of 126 to 130. So, if you used white, R255, B235, G 245 would be "OK". R243, B243, G255 would not.
Step 5: If Step 4 failed, adjust the settings on your camera appropriately (change the ISO or change the Shutter/Aperature or change the Exposure compensation), then go back to Step 2. Keep going back until Step 4 is a success.
Now your camera is properly exposed. If it is not, forget wasting time on the next steps. There is no point going on if you don't get step 4 correct.
Step 6: Tell the camera to "White Balance".
Step 7: Take a picture and load into your computer.
Step 8: Check the file. Like Step 4, but now, not only should they AVERAGE in the range of 240 to 245 or 126 to 130, but all three values should be within 2 or 3 points of each other.

Want to get fancy? Are you in a studio? Want the absolute best? Buy a color meter, then measure the color of each of your flashes, then, if they are more than 100degrees Kelvin apart, put Gels in front to bring them all to the same color. THEN do a white balance for your lights. And check again every month or so to make sure the color isn't shifting.