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There are several white balance settings on the Nikon D80 including one that is automatic. I normally don't use it although I wonder what settings others use.
So the question: What are advantages/disadvantages to use auto white balance compared to manual modes? And what do you usually use and why?
For all the discussion about which camera white balance setting to use, I think it is important to note that, if you are shooting RAW, the simple answer should usually be "Always use AWB". The reasoning for this is because white balance is an easily correctable thing in post processing when you shoot in RAW. Even if you do use the "Manual" or "Custom" white balance setting of the camera, the camera is still making an educated guess...it is just making a more informed guess. Custom WB can still result in incorrect color balance, and there are times when it can be as off as AWB.
In contrast, using AWB in camera, and correcting white balance during post processing with RAW, gives you FAR more control over the final white balance than you can possibly get by working with in-camera tools. When using a tool like Lightroom or ACR+Photoshop, you have the option of using a "white balance color picker tool" to select the area of your image that actually is white, and the software will correct the rest of the image from there. It is difficult to get more accurate than that.
Additionally, if you take a "white balance baseline" photo wherein you include a gray card in your scene, then remove the gray card and take the rest of the photos for that particular lighting scenario, you have even more accurate control over white balance during post processing. Simply use a white balance picker tool, select the gray card. Copy the white balance setting from that initial baseline photo (after its been corrected) to the rest of the photos shot under that lighting to apply the correct color balance (in bulk, if you have a tool like Lightroom.)
The case where AWB won't necessarily work all the time is when you can't or don't shoot RAW, and use JPEG instead. Correcting white balance in a JPEG during post processing is difficult at best, and can be impossible at worst. In such cases, you might try to use a custom/manual WB setting. If your camera supports it, you may also want to tweak the custom WB offsets (color temp. along the blue/yellow axis and color tint along the green/magenta axis) to improve the results.
White-balance options can be divided into 3 groups:
Auto: Let the camera guess.
Presets & Kelvin: Tell the camera what you know.
Custom: Make the camera measure it.
Personally I do not bother much with the presets:
Automatic white balance usually performs poorly as the camera doesn't know the difference between a yellow object under white light and a white object under yellow light. All it can say is that if the image as a whole contains a lot of yellow tinted colours then that may be the result of a yellowish light and so set the WB accordingly.
This scheme is easy to confuse when you have lots of strong colours in the objects you are photographing.
If you want to automate your white balance, buy/make a grey card and shoot a custom white balance image with it - that way you have removed one of the unknowns from the equation leading to much better results.
The only advantage of automatic white balance is that you don't have to do anything yourself. The principle disadvantage is that it has to rely on assumptions and guesses as there is not enough information to distinguish between object colour and lighting colour.
It's worth stating that camera white balance settings are only really important for people who shoot JPEG, if you shoot raw you can choose the white balance later when you're at your computer. It can still help to shoot a grey card when working with raw however.
The auto-white balance algorithms in most cameras handle some situations very poorly. As with metering, the camera can't really know how the scene is supposed to look; it can just guess. Or rather, not even guess, but apply a simple algorithm. The one used in Gimp is like this:
That's not very smart, but tends to work surprisingly well. The auto-WB algorithms in cameras are probably more sophisticated but I expect they use the same basic idea.
So, in some situations, the camera can get it really, really wrong.
In these cases, setting the white balance manually can help. However, they can be too strong, and produce casts that you didn't mean. (One can actually use that for artistic effect.) Setting the WB manually against a gray card (or something neutral in the scene, in a pinch) is ideal.
Another important use is when there's mixed lighting and you need one part of the scene to be right. This is a hard situation where it's impossible to do the right thing across the frame, and so it's nicer to be in control of the decision yourself rather than doing whatever the camera works out.
My camera (the Pentax K-7) happens to have one of the best auto-WB systems available. It's amazingly good. It may be because it has an actual-light-color sensor used in autofocusing — it's unclear whether this is used in WB or not, but it seems like it might be. Either way, auto-WB generally works so I well that I don't have to think about it.
However, sometimes it goes wrong. As I just answered in another question, this is one of the reasons I shoot JPEG + RAW. Then I can go back and fix anything that didn't come out right. Generally, I do this right in camera later.
* oh, that's confusing, I know — high color temperature is of course more blue and less yellow, whereas the opposite is used traditionally to describe the feeling of different hues. Red, orange, yellow are warm colors, but a low color temperature.
Like usually in manual vs auto choices, manual gives you control over the final choice. In auto WB, the camera evaluates scene for each individual image and tries to adjust colors so the tonality of light would not affect how subject is shown on the photo. This is convenient, but unsuitable if the WB estimate fails, does not match your vision of the desired tonality or you need constant setting for a series of images.
A classic example where auto WB has a different vision than the photographer is during sunset or sunrise. While the human finds the overwhelming warm tones pleasing, the auto WB will work hard to "balance" the colors by reducing the red and boosting blue, resulting in a bland grayish picture. Using custom WB with a gray card would have similar effect - the camera would try to show the gray color "as usual" and hide the specific tone of light. By forcing the camera into some preset (my preference: "daylight"), the picture will be more like what the photographer perceives.
I have often found "cloudy" to be a handy preset when taking photos outside. It gives neutral colors in overcast situations, warm colors in sunshine and slightly cool colors in shadow. While these colors might be unsuitably off for a fashion magazine, I find they pretty well convey the feel of the light and scene.
Using a flash, the auto WB might decide to go for preset "flash" balance. This is certainly not what you want if you have correctly gelled your flash to match the ambient light. With mixed lighting of flash and ambient light, a quick snap with "daylight" WB and flash off will help you evaluate which gel to use, and after that use either custom or preset WB according to the light.
When shooting in RAW, WB is mostly irrelevant as the setting is only used for preview and as a "starting offer" in post-processing. So you might be okay with auto WB, or you might prefer to use WB preset UniWB (if supported by camera). That one is optimized to give you colors in preview unadjusted as they were captured by sensor, thereby making your color histogram more closely match the data that is actually saved.
I usually set WB as follows:
To extend Matt's reply, a lot depends on your camera. As Matt says, the automatic white balance on many cameras performs poorly. On the other hand mine, like many other cameras, performs very well.
So, in my case, I normally keep my white balance on automatic but switch to manual in tricky situations like:
- mixed lighting such as incandescent and fluorescent
- the scene is meant to have a colour cast, a disco comes to mind
- an uneven lighting distribution that from experience I know won't be rendered well
- product shots in a light box where I must get the colours absolutely true to the original.
Since I shoot in RAW I always get a second chance during RAW conversion.
The problem with manual white balance is that I keep getting caught with the previous white balance settings that get applied to the current shoot. Automatic white balance frees me from this worry.
Shoot in Manual WB mode when shooting video, otherwise you might get changing colors if the Camera does adjustments to the WB while shooting and the light is changing or something like that.
