Shooting and processing a light-trail image

Photographing is sometimes described as the art of painting with light. Capturing cars at full speed as dusk falls is a good way of letting vehicles paint the strokes for you. From a viewpoint perspective, I’m fortunate to live only a few miles away from a bridge that affords an unimpeded, safe and interesting view of the M3 diverging from the M27 in Hampshire. This is where I shot my image River of fire, which recently trended Popular on 500px.

Time is key in two respects:

• you need sufficient vehicles to create a reasonable number of trails per exposure – but you certainly don’t want traffic so heavy that it grinds to a halt;
• you need to take your shots at dawn or, more practically, at dusk, so that cars have their lights on without the sky being pitch black.

High summer and mid-winter evenings are thus not so good for this genre – beyond city limits at least – because the sun sets either well before or after rush hour. Later March, however, is ideal because the sun sets at around 7 pm in the UK.

Post-processing is unavoidable because you need to combine several exposures. In this instance, I used six 10-second exposures taken at f11 with an ISO value of 100.

It goes without saying that shooting raw files will yield better results. This is how I do it:

1. In Lightroom or Adobe Camera Raw, optimise the first one and sync your Develop settings with the other files.
2. Open them all as Layers in Photoshop and move the one with fewest trails to the bottom of the stack.
3. Use the Align feature in Photoshop to prevent blurring of road markings, signs and so on.
4. Change the blending mode of the rest of them to Soft Light so that all the trails show through.
5. Mask out any trails from high-sided vehicles, which obscure road markings.
6. Clone out any roadside litter or other distractions from the base layer.
7. Flatten the image, save it and return to Lightroom, where you can make any further global edits necessary to your final image.

I hope you found this useful. Feel free to share links to your light trail images and tips about processing them in the Comments.