A Lesson in Light

Street Scene, 2010

When I was in Providence back in September, I took a lot of pictures at night. One of the challenges of photographing at night is getting the light right. It’s not just a matter of lights and darks, but rather a matter of also considering the various light sources in the scene.

No doubt you’ve noticed that different kinds of lighting fixtures cast different kinds of light: incandescent; fluorescent; halogen, mercury vapor and so on. The first time you took a picture in fluorescent light you probably wondered why it came out looking so green. That was the result of the jittery motion of excited atoms creating light that is amplified by phosphors. In the old fixtures, they cast a green or blue light. In modern compact fluorescent light bulbs, the phosphors are mixed to create a more “cool white” light.

These differences are noticeable to your eye. But your brain adjusts them to make sense to you. Studio photographers compensate by using uniform light. Cameras are smart these days. A long nighttime exposure of the sky will pick up light blues your eyes wouldn’t see. But the camera still isn’t as smart as your brain. To film or the digital sensor, each fixture casts light at a different temperature and consequently shows up a little differently in your image.

In the photo above, there are at least three different types of light: the lamppost at right, the porch light in the middle and the light down the street to the left. Each one casts light of a different temperature and therefore comes across as a different color in this digital image. I’m not up on this enough to remember which is which other than to observe that the lamppost looked like incandescent; the porch light was a bright white light and the streetlight to the left cast an almost yellow shade.

By the time the sensor in my camera saw these different lights, the lamppost became pink, the porch light blue and the street light to the left yellow-green. To be honest, I kind of liked that. As long as there were no people in the scene to be made ghoulish by the blue light, the result was interestingly atmospheric.

But I wanted it to be more realistic.

Fortunately, programs like Photoshop can help you here. You can turn your faith over to the computer program’s pre-sets if you have just one kind of light to deal with, or you can adjust the colors separately if you have several kinds of light to deal with. That’s what I did. I reduced the blue saturation in the porch light and the red saturation in the lamppost. Each person's taste is different. I chose to leave a hint of both the blue and the pink to give the picture a little more interest.