There’s nothing like a good shaft of light to add production value to your cinematography. But you can’t just shine a lamp through a window and expect to get Hollywood shafts. Here are the essential conditions you need:
1. You need focused light, i.e. a lamp with a lens. Source 4s work extremely well. HMI or tungsten fresnels will also do the job, and sometimes Dedos.
2. You need a smoke machine or hazer to volumise the light. A cheap one from Maplin will work, but as a general rule the cheaper the machine, the more its output will be wreaths of smoke rather than just thickening up the atmosphere. However, given time to disperse and some vigorous wafting with a flag or the clapperboard, any smoke will work.
3. The smoke/haze needs to be backlit. The closer the light source is to being directly behind the smoke, the more the smoke will show up. So shoot towards windows.
4. A dark background will show up the smoke best. If you’re shooting in a house with white walls then you’re probably flogging a dead horse.
5. Keep other light sources away from the shaft. Competing lamps can muddy the shaft of light or maybe make it disappear altogether. Often I find that shafts of light work well as background interest, with the actors well in front of it, lit by other sources.
Follow all these guidelines and you’ll get lovely shafts of light every time!