It all seems so easy in these digital times of photography. Hit the release button and there you go with a fantastic food shot. Load it up to your computer and almost in no time you can take a look at the results.
...but sometimes taking a look at the results ends up with an unpleasant surprise. What looked great through the view finder or on the little camera screen, now has a not appealing touch into yellow, blue or green. Or you get responses from others telling you, that your photos have a yellow, green or blue color cast. Where in hell did these pretty colors turn into something else?
The answer is very easy: The colors that we human beings see are or can be different from the colors cameras or computer monitors "see, produce or display". The trick is, that we learned to see colors right, even if they are different in the "real" (physical) world. Yes, that can be true. Make a very simple experiment. Take a simple white plate and photograph it with you camera outside on a bright day around noon and then in the house under a simple light bulb. Don't change the camera settings. Load the photos to you computer and take a look at them. The one outside should be white (with default settings of your cameras turned on). But the one taken inside will have a yellow cast. The plate isn't white anymore but more or less yellow. You eye has seen a white plate all the time, because you have learned that the plate is white. Even under physical conditions, where the plate isn't reflecting light, so that it will appear white, we think it is white. This is great for us, because we don't get confused by color changes due to different lighting situations*, but for photography it means to learn the basics about color balance - mainly White Balance. We have to adjust our camera to see things right.
1st statement: Colors in the "real" (physical) world can be different from what we think. Cameras can only display the colors of the "real" world.
What does this mean for food photography? We have to adapt our camera in some way to overcome this physical problem. We have to make our camera ready to see the colors as we want to have them. The keyword here is White Balance. I do not go into the technical background on the meaning of color temperature. It isn't necessary for what we have to do. Important is, we have to change the camera settings in a way, that the camera produces "true" colorsm, so that white is white, blue is blue...
2nd statement: if you never have read any manuals READ the part of your camera's manual on WHITE BALANCE. Do it! If you don't know how to use the white balance feature of your camera right, the colors coming out will always be hit or miss without any control. So, read your manual.
Every camera has some pre-settings for white balance based on general assumptions. These pre-settings often come very close to "reality" and produce good results, which can be improved by some easy postprocessing steps later on. You will find settings for "cloudy day", "sunny day", "in shadow", "tungsten lamp" and others symolized by little pictograms. And you will find a "manual white balance". Try the pre-settings under different conditions to get familiar with them. Use some simple objects for this training: a white plate with some fruit on it for example. Take shots in your usual photography spot. Compare the results.
Now read your manual on "manual white balance adjustment". This is the fine tuning of your camera. Believe me, once you know how to use the manual white balance, you will never use the pre-settings. The idea behind the manual white balance is, that you adjust your camera depending on the momentary light situation by using a so called "gray card". And if you don't have a photographic gray card, you can use a sheet of white paper instead, which oftens gives you good results too. During manual white balance setting steps you "photograph" the gray card (white paper) and the camera is adjusted to this gray/white. Now the white balance is adjusted and colors should be as "true" as possible. At first this might take some time, but after a few times, you will be very fast doing it as a routine step in photo shooting.
Why a gray card? Everything in photographic lighting is based on measurements resulting from reflection of ligth from a defined (photographic) gray card, which reflects defined amount of light. It is a technical agreement on how to measure light, lighting, reflections in photography. You can get these gray cards in every photoshop for reasonable prices.
Now your camera should produce photos with "true colors". But when you take a look at your photos on the computer monitor, they still don't what you want them to be?
3rd statement: you also need to calibrate your computer monitor to display "true" colors. Yes, also the monitor might not display the colors correctly. Most monitors are calibrated during manufacturing, but during the lifetime of a monitor this calibration might get lost due to technical limitations.
I will not go into detail here on monitor calibration and how to do it. I have written about it in the Food Photography Club of Flickr in the thread "Tips, Tricks & Opinions: Monitor Calibration". There you will find more information about it.
If you remember, in my title I have mentioned "color mood". Why? Because sometimes true colors are not what we want to have for compositional reasons. Maybe you want a warmer (more yellow, reddish) color mood to get the impression of a warm day or for a more cozy feeling. Or you would like to have slight blue cast for the idea of a cool morning scenery. Or you just want more popping colors, e.g. an aggressive red, for emphasizing a certain idea. For all these reasons and photographic ideas you may want to change the color mood a bit from neutral (white balance) to a different color mood (warm, cool). Also this can be done with many DSLR (digital single lens reflex) cameras. After you have adjusted manually the white balance, you can manipulate it towards more red, yellow, blue, green... Or you can do it during post processing your images by changing the color balance manually.
My personal opinion
There is nothing more annoying than a wrong white balance in food photography. Green looking potatoes are not very appealing to me. Or who wants to look at a blueish vanilla ice cream? Did a greenish looking steak makes you salivating? White Balance control is an absolute must in food photography, because we are connecting certain colors with different flavors and taste. There is a correlation for me between color and if a food is appealing to me or not. And for me there is nothing worse than to ruin a food photo by mismatching the color balance (which can not be post process later). I always check white balance before and while shooting. Especially, if you are using natural light, color balance can change from one moment to the other. So, if you like just one take home message from me, my message for today is: Adjust and control white balance for food shootings very carefully. And better check it twice than to miss it.
* Funny thought. After you have read my post on color and white balance, try to imagine how dificult it would be to describe the color of a simple thing like a plate. It could be something like this: "I have bought yesterday a plate, which has a velvet soothing white on a bright day, not too cloudy, around noon. This changes to a wonderful yellow on our dining table with our new light bulbs at a color temeparture of 2700 Kelvin. But if I would have known, that it is aweful blueish on early sunday mornings around 8am, I would never have bought it"
If you are interested in details:
On Color Temperature
On Gray Card
On Color Balance
On Understanding White Balance