1 Hang your torch
Attach a small pen torch to a piece of string – the thinner the torch the better the results. To make my torch’s beam sharper, I created a small cone from black card to funnel the light. It’s important to keep the torch’s bulb parallel to the ground, so you may need to secure the string so it hangs down. Depending on your lens’s focal length, hang the torch close enough to the camera so the light’s movement fills but doesn’t leave the image frame.
2 Camera set-up
Place your camera laying on a surface, pointing directly towards the overhead torch; try to position the lens so the torch hangs centrally. Using a wide-angle lens, such as the Nikon 18-35mm f/4.5 I used, gives your camera more field-of-view to include the swinging torch when you get it going. It’s a good idea to attach a UV filter to your lens too on the unlikely chance the torch comes loose and lands on the lens, it has modest protection.
3 Camera settings
While the room lights are on, focus on the torch before switching to manual focus to stop the lens hunting in the dark. Set f/11 for adequate depth-of-field, ISO 100 and Bulb/Timer mode; a remote release can help too. You’ll be in control of how long the lens will expose the patterns for, but initially aim for 20-30 seconds and shorten this if you begin exposing the ambient light and lengthen it if the trails aren’t burned into the exposure.
4. Take your shots
Turn off all ambient lights and swing the torch. Once the movement has settled to a gentle sway, fire the shutter once to start the exposure and again to finish it. If you want to add more shapes and colours to the exposure, you can place a sheet of black card over the lens mid-exposure and switch the type of torch, add a modifier, try different coloured gels or swing the torch in a different direction. Remove the black card to finish the exposure.