We don't usually often think of it this way, but photography is really about drawing pictures with light - which means that you can literally draw your own pictures by adding light to a photo in a controlled way.
Many years ago, before digital photography, I used to experiment with this sort of photo using long exposures and a torch.
In the past, I've shown how to mimic that effect digitally. This week, I thought it would be fun to do it the old-fashioned way and actually 'paint' with a torch.
Getting set up
Painting with light is more art than science: you can get great results with almost any kind of camera, and experimentation is key. Unlike the kind of experimentation I remember from school physics, though, this is actually fun.
To get started, you'll want a digital camera that has some sort of long exposure mode. Ideally, you'll be able to set the shutter speed to 8 or 16 seconds. I've found that 8 seconds is barely time to do anything, so honestly, you'll get more satisfying results if your camera has a 16- or even 30-second exposure setting.
You'll also need to set the camera on a stable surface. Since you can't really hold it still for 16 seconds, a tripod is ideal. You could also just set it on a desk, table, chair, or any other surface that isn't going to move around during the exposure.
And finally, you'll need some light sources. You should gather one or more torches, and, if possible, an external flash unit. Don't mount the flash on the camera - you'll want to hold it and trigger it manually.
Taking the shot
Now that you have your supplies ready, wait for nightfall and position your camera for a photo. Your surroundings should be as dark as possible, such as in a room with the lights turned off, or outdoors, away from street lights. Press the shutter release to start your long exposure, and then use a torch to 'inject' light directly into the scene.
One way to use your torch is to mimic a sci-fi 'phaser' effect, like this old photo from my film days. I achieved this shot of my friend Paul 'phasering' Bob by positioning them in total darkness, starting the camera exposure, and illuminating them with my handheld flash. Then I carefully moved a torch in a straight line from Paul to Bob. For a finishing touch, I removed Bob from the scene and fired the flash again to achieve the impression that he was disintegrating.
For a modern update with a digital camera, here are some shots I took just this week with my daughter. Here she is shooting beams of light from her hands.
And this one shows the kind of cool, unpredictable light trails you get as a result of random variations in the way you hold the torch.
Controlling the light
Since this technique relies on you moving a torch around in the dark, clearly it's not possible to get perfect results every time - that's why I say you need to experiment. You can stack the deck in your favour if you remember to choose your camera settings wisely.
The shutter needs to be open for a long time, so that means the only aspect of your camera you really have control over is the aperture. If you use a small aperture (which equates to a large number, like f/18), the effect of the light will be diminished. A large aperture (small number, like f/4) will admit a lot more light, and that means any ambient light will illuminate the entire scene. But it also means the torch will appear brighter, and you might pick up ghost images of the person moving around with the torch. Start with an intermediate aperture, like f/8, and vary it to see how different values affect your photos.
Pointing the torch
Finally, the way you point your torch can give you dramatically different effects. I recommended that you point the torch directly into the camera lens, because that will give you the most immediate and dramatic result. But as an alternative, try shining the torch at objects in the scene instead. In a perfectly dark room, for example, you can experiment with selectively illuminating subjects.