Studio lighting is a science as well as an art. After picking up several books on the subject, I’m starting to get used to some of the terms like bounce and snoot… but I’ve still got a long way to go, there is so much to take in.
Let’s start with the somewhat obvious. Different light has different color characteristics. Anyone who’s worked in an office is certainly familiar with the blueish glow given off by florescent tube lighting. Or, you may have heard of $1 million dollar light, the term that movie studios use to describe the golden quality of light just before sunset (it’s called that because at the time the phrase was coined, it took about a million dollars to replicate the same quality). The lighting you use will have a dramatic effect on the color composition of your photos.
The color of light is referred to as color temperature, and it is measured for some ungodly reason on a degrees Kelvin scale. Kelvin temperatures are actually negatives, so warm tones are between 1900 and 3200 degrees Kelvin. Neutral tones between 3300 and 4000. Cool tones are 4000 to 6500. If you think about natural light for a second, you’d put sunset at the far end of the warm spectrum and a Seattle overcast day at the far end of cool.
Note: Setting the color temperature in a photo editing application adjusts for the light the photo was taken in… for example, if you set it to the cloudy end, it will make your photo warmer assuming that it if you took it under cloudy skies it will look too cold. In Photoshop’s Raw editing tool, this is particularly confusing because you enter a lower number if you want your image cooler and a higher number if you want it warmer.
Now, you might be tempted to think that if you want neutral colors… that is your whites to look white… that you should go with neutral light. Unfortunately, it’s not that simple. Warmth and coolness do affect how color appears, but not in a uniform fashion. Some warm bulbs give the truest overall color reproduction. The lighting type (and even the quality of the individual bulb) has a lot do to with it as well, and as this chart shows, it’s pretty nutty. The quality of rendering is measured on a scale called the CRI – lower numbers render less color and can look washed out. Higher numbers indicate that color will come through naturally. There’s lots of math involved with this, and if you are really interested, Wikipedia has some great explanations and equations on why this all makes sense.
As for me, I’m going to take their word for it. For indoor, artificial lighting, incandescent bulbs (like this one) rate the highest, closely followed by tungsten halogen. Daylight florescents (those cool spiral energy saving bulbs) aren’t quite as good, but are ok.
Here’s a sample of tungsten halogen and natural daylight:
As you can see, with proper setting of the white balance, they are pretty close but the natural light is warmer. (You’ll have to ignore the fact that one is backlit and the other side lit… my ‘studio’ has it’s limitations). In particular, notice the blue hints at the top and on the handle of the pitcher in the tungsten version. I could correct those in Photoshop fairly easily, but then other parts of the photo might start getting too yellow. In the natural light, you can see more warmth in the shadows, particularly in the lower left corner.
So, different lights, different color tone and different color rendering.
Unfortunately, that’s not all. There is a different kind of temperature you need to be aware of… that is actual heat given off by the lamps. There are hot lamps and cool lamps. Hot lamps (like the incandescent and tungsten halogen listed above) run continuously which can be great because it allows you to see exactly what the light will look like and the quality of the light is warm and inviting. But they do get really, really hot and that can be a problem for food photography, particularly for things that should stay cool like ice cream, fresh herbs, salads, beverages and so on.
Cool lights (strobes) on the other hand omit quick, high intensity flashes of light. The light often has a blue cast, and without some sort of color balancing is likely to give you very cold looking results. But, the food stays fresher, longer. Strobes are also typically harder to work with because you can’t see what the end effect will be until the strobe fires.
Despite the fact that you have to work quickly, beginners are typically recommended to start with continuous, hot, lighting. It’s easier to get a feel for how lighting positions and strengths will affect your photography and the lighting systems are significantly cheaper.
For the most basic continuous lighting setup, there is a fantastic article here on using work lamps that you can find at your local Home Depot. Two dual head work lamps and stands that you can use indoors or out will run you only about $100. Jesse, the I Faked It site author, also has some great tips on photoshop… definitely worth checking out.
I’m using a slight step up from that… the Lowel Tota-Pak tungsten halogen lamps. This set comes with a small umbrella and reflects light to the subject rather than lighting it directly. The result is a really nice soft lighting. Another thing I like about these are the size. They are small, so I can move them around my very small kitchen without much problem or even collapse the stands and set them right on the counter. I also recommend getting a small spotlight to go along with this set, since the indirect lighting doesn’t let you highlight specific areas much.
I haven’t shot with more than this, and I’ve never shot with strobe lighting, so I’m reluctant to make a suggestion on those. If you have a system you like, please feel free to talk about it in the comments!
Once you know what light you are shooting in, don’t forget to set the color temperature on your camera… If you do forget (like I always seem to), you’ll have a lot of extra color correction to do in your shots.