A guide to catching stardust - How to photograph Star Trails

How to photograph Star Trails

There are many elements coming together serendipitously in this image. You may notice the left side of the tree is bathed in a beautiful even light, which was from the full moon, before it was eclipsed to reveal the glory of the cosmos in the ensuing hours of darkness. The light on the right side of the tree is from a hurricane lantern I had placed there. The entire process took about five hours to capture, and it felt like an act of cosmic communion, where the dance of the moon and stars played out above an ancient baobab tree, deep in the wilds of the Okavango Delta.

Star trail images always make for compelling subjects, especially when you have an interesting static object to use as a visual anchor in the frame. Bear in mind that in the Southern Hemisphere, the stars rotate around a southerly axis- so point your camera in that direction to get a circular effect as they move across the heavens.

In order to get this shot, I combined a very technical approach with an unusual, but expected, natural phenomenon: a lunar eclipse. This gave me two advantages: light from the moon as it was being eclipsed would paint the side of the massive tree silver, while the darkness of the eclipse would reveal the stars. This sequence took hours to photograph, and the on-the-ground technicalities involved placing a lantern at the base of the tree where it wasn’t in view to light the other side of the tree, thus giving it shape. The camera was firmly fixed on a tripod, and I set an intervalometer to take a sequence of 30-second exposures one after the other. By breaking it down into chunks like this, I was able to avoid burning out the images with moonlight, as well as avoid spoiling a 3-hour single exposure by an unexpected intrusion into the frame, like an owl flying past the lens. The result was 180 frames, each at 30 seconds exposure at f/4, which I then put into PhotoShop to create the final image.

The really technical part came next: to individually open and layer 180 consecutive files will take forever, unless you use ‘File’ – ‘Scripts’ – ‘Load files into Stack’. This automates the process, and results in a single file with 180 layers. These layers are all opaque, however, so the next thing you do is select one layer in the layers window, and using the drop down layer style menu, select ‘Screen’. While that layer is highlighted, right-click on it, and select ‘Copy Layer Style’. Next, deselect that layer; select ALL the other layers, right-click, and select ‘Paste Layer Style’. Finally, flatten the result into one layer, and there you have it.

Depending on your processing power, you should have an awesome image in a few minutes or a few hours- my MacBook Pro took 8 hours to perform this feat with all those high-res files in the stack- twice as long as it took to shoot the original sequence!

To sum up, shooting in low light can be a technical challenge, but with the right know-how and utilising the current advances in digital camera technology and software, you are able to set your imagination free and create some truly stunning images!