There’s no better way to capture the hustle and bustle of a roaring city than by shooting traffic trails.
This technique requires your camera to be locked off on a tripod (or similar), so you can shoot the same scene over and over to build up the layers of traffic – you’ll then combine the different exposures in Photoshop.
It needs to be dark when you photograph your traffic trails. The hour after sunset gives good results, as there is still a little colour in the sky. Shooting after sunset allows your camera to pick up the white light from car headlights as well as the red from the brake lights. Whether you record white or red trails will depend on which way the traffic is flowing, and a shot with perspective and room for the cars to move into will help you achieve stronger trails. For smooth traffic lines you’ll want to frame up on an area of fast-moving traffic. Shooting a motorway from an overpass is the classic example – cars move quickly in both directions here, so you get the red and the white lights.
To shoot the trails you need to set up your camera on a tripod and frame up on a scene that traffic will pass through. Don’t put yourself in danger, so frame up somewhere safe such as on a pavement, and make sure your tripod isn’t spread out onto the road. Take a friend with you if you’re worried about having your equipment on display at night.
Go into your camera’s shutter-priority mode, set an ISO of 100 and turn on the 2sec self-timer. It’s now time to set the shutter speed. Between 5sec and 10sec works well. You’ll be recording lots of exposures so you can build up the effect of multiple trails in Photoshop. When you set the shutter speed make sure your image isn’t under- or overexposed – the aperture value will usually blink on most models to tell you the shot won’t be exposed correctly, so bear this in mind. When you’ve set the shutter speed, note down the aperture value. Now go into your camera’s manual mode, set the ISO to 100 again, and insert the shutter speed and aperture value you just noted. Going into manual mode stops these values fluctuating so you get consistent exposures.
With the 2sec timer engaged you want to focus on the road where the cars will be and then switch to manual focus to lock it off. Because of the 2sec self-timer you need to press the shutter before the car enters the frame – it takes a bit of practice, but it stops the images from being blurry caused by your finger pressing the shutter button. One way to get around this is to use a remote shutter release cable, which lets you shoot instantly and won’t shake the camera as you start the exposure. Take plenty of images, experimenting with different exposures to get a good trail length. Make sure the trails go through the whole shot, and don’t suddenly stop or begin halfway.
When you’ve got several trails you’d like to combine you need to open up Photoshop and go to File>Automate>Photomerge. Click Browse and navigate your way to your trails. Select them and hit OK, then make sure Layout is set to Auto, the Blend Images Together box is unticked, and then hit OK. Now in the Layers panel change the blending mode of each Layer to Lighten and you’ll see the effect build up.
Dan Mold is a professional travel and wildlife photographer and a regular contributor to Practical Photography and Digital Photo. He has recently returned from an epic adventure around Asia and Australia. See more of his work here.