Star trails – another beginners guide.

For many including myself there is nothing more wondrous than the night sky. For me, the idea that I’m capturing those precious few photons that have made the journey through millions of miles of space, just to land on my sensor is magical. You may have seen examples of shots like these and wondered how they are achieved. Hopefully I can put you on the path to creating your own star trails too.

This shot was taken in Thurstaston, Wirral roughly between the hours of 2 and 4am. I had been playing with smaller star trails shots and wanted to try a much wider lens so I needed a completely clear sky.

A shot like this cannot be taken as one exposure, the sensitivity of the digital sensor would fill the image with noise and overexposed everything during the 2 hour path of these stars. Instead, I took a series of just over 230 shots, each one 30 seconds long, I could have gone with longer exposures but for reasons I will go into later that wouldn’t work for me. The separate images are then merged in photoshop to create this single sweeping effect. With hundreds of points of light racing around the north star.

So. What do we need for an image like this.

A time and a place
Obviously we need a clear night, and they a difficult to plan. If you know you want to do this have your gear packed in case you look out late and it’s perfect. Try to pick a night when the moon is at its smallest, you don’t want it anywhere near your frame if you want to see all those stars.
As for a location, you’ll want somewhere dark as far away from light pollution as possible (the red colour to my image is actually Liverpool), and somewhere safe. You’ll be sitting for a long time, with your camera, going nowhere so pick somewhere you won’t be disturbed. Of course you may want to put something in your image, like a landmark, or silhouetted landscape like here. It helps to have something in the foreground to give a sense of what we’re seeing, and the distance.

Camera
I used a nikon D300 for these shots, although I also have a full frame D700 which produces much cleaner images, but i was using that to try a variety of shorter exposures during my long wait. Virtually any DSLR will be capable of star trails. The advantage of a camera like the D700 is it allows either timed multiple capture, or a huge memory buffer to shoot continuously which is what I did. This just gives you a little longer between interactions, and so less chances to disturb the shot.

Lens
I wanted to shoot as wide as possible so I opted for the Tokina 11-16mm 2.8, an ultra wide ‘only just a’ zoom lens that I adore. It’s incredibly sharp all over the frame and suffers from virtually no distortion. If you shoot DX and are a wide angle fan. Test drive one of these. Most star trails will be shot using a prime lens, for optimum performance at wide aperture. You can get trails with virtually any lens but starting off with a 50mm 1.8D or 1.4G is a great way to see results without spending too much. To focus on the stars, it will help if your lens has an infinity mark, if not some trial and error may be required.

Tripod
I can’t stress this enough, use a heavy, sturdy tripod. This shot relies on the camera not moving at all, I used a tubular alloy tripod with ball head adapter, weighed down with a heavy kit bag. Make sure everything is tight and it does not creep over time.

Extras
To be honest, this is less about your equipment and more about keeping sane for 2 hours, while clicking a button every five minutes. Its exciting when you start, but you’ll be fighting the urge to finish early when you’re cold, lonely and bored. Audiobooks are good. I was in the middle of nowhere taking this and there wasn’t any light so don’t count on doing much else.

So. You have your camera, lens and location sorted. You’ll want to sort a few settings:

Manual mode – you want every frame to be the same, every other mode will allow the camera to overexpose your mainly black image.
Manual focus – again, your camera probably can’t focus to well on a single point light source like a star. Set you focus to infinity, or use trial and error to gradually bring the stars in focus by checking your LCD.
Select a white balance – as the stars change position relative to the frame, auto white balance will vary the colour of light in your shots, to prevent this. Pick a white balance that looks good and stick to it, or shoot in raw and sync them all later.
Shooting mode – you may have an interval timer setting to allow you to program shutter timing and amount of shots. The Nikon system is very confusing and badly set up, you may find it best to use continuous shooting mode with a shutter release lock. I use cH mode (continuous high speed) to minimise time between exposures.

Ok enough prep. Lets take some shots. I started here by finding the north star Polaris. The north star is above the pole and so provides a perfect centre for our ‘rotating’ stars. We are looking for the longest exposure we can get with an acceptable level of noise and detail. I shot these at ISO 400, f4 30s. I focused my Tokina lens to infinity and took a few test shots. Minor adjustment was needed to fine tune, easy when you zoom in on your display.

My tripod was setup in a rocky dip in a path, in the middle of woods, on top of a hill. because I was using the almost ridiculous 11-16mm Tokina DX set at 11mm (effective 17.5mm on FX) the angle of view is 104 degrees. This means with the camera tilted slightly towards the sky I could limit the light pollution at the bottom of the frame and get a huge expanse of sky into the shot.

With the 30s exposure on continuous mode, the D300 will fire 100 shots, in real terms this means locking your shutter release and waiting for 50 minutes before readying yourself to release and re-press. I advise doing this slightly more frequently to avoid gaps in your star trails.

Then you wait.

And wait.

Until you get cold, bored or are satisfied that you have taken enough shots. When this happens, try to stay a little longer. Do you really want to go through this all again?

When you are finished you may have hundreds of shots, hopefully all the same exposure.

Now you want to put them together into one image to show those amazing trails. You can build your own photoshop action by importing each image into a new layer and using the ‘lighten’ layer mode. Or look up and download the star trails action here. You can find a video of how to use it here.

I hope this has been helpful, this may not be everything you need to know, but it should get you started. It’s a lot of work for one image but I hope you agree it’s worth it.

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