So what is a star trail...A star trail is a photograph that is taken over a long period of time, anywhere from 3-4 minutes through to 3-4 hours plus, and it captures the movement of stars across the sky thanks to the rotation of the earth

How to do it...

There are two distinct ways to approach the capture of a light trail, the traditional way is to open the camera shutter for a extended period of time to allow the camera to record the movement of the stars across the sky, and it is possible under the right conditions to achieve exposures in excess of one hour in a single exposure to capture the stars movement. A note of caution with this method is the risk of your camera/sensor overheating so please take this into consideration

The other way, that is more popular and more accessible to most photographers is to go down the stacked approach, this is where you take a series of single exposures and then layer each one on top of the other to create the effect of a longer exposure time, and this is the way that the Kenilworth Castle photo above was achieved...

With a stacked exposure it is possible to cope with even quite high levels of light pollution...There are a number of ways to do the stacking but there are some rather useful and free pieces of software that will manage the stacking process for you, I'll come to those in a little bit.

Kenilworth Castle Star Trail

The Kenilworth photo is made up of 245 x 30 second exposures, at f/4 and ISO800, but you should never worry about your settings too much as each situation will always need slightly different settings, it's all about trial and error to get the settings you need. It's important to remember that your out for a while to achieve a decent trail so what is five minutes at the start to get it right

The Kit....what you need

The minimums

§  Camera with manual controls

§  Lockable shutter trigger/release

§  Stable Tripod


Those are the only three things that you have to have for a star trail every thing else is purely advisory.

I also like to take

§  Something warm, remember it is night time

§  A drink and maybe food

§  A chair

§  Some company 


You’re out for a fairly long time so all these items are really advisable, especially the company thing, if you’re going to be out for many hours at night it's a good idea to have a little bit of company too keep you sane and for the added security factor

Setting Up...

...when you have found your location that you want to trail get set up for the exposure but take your time, this is a little check list I try and follow

  • Check your tripod is steady/stable
  • Check your composition
  • Check your focus
  • Check your settings (ensure you have your camera set to continuous shooting so that it can take photo's one after each other)


The first thing to make sure of is that your image is in focus, and that you like the composition, if you  only discover its out of focusI after two hours and it will really annoy you

I would suggest is setting your camera to Bulb, Max ISO and running an exposure to check both focus and composition, I've found 60 seconds to be about right for this, and repeat this process until your happy with focus and composition, them move on to tailor your exposure settings for the actual photo

To make your camera take multiple exposures one after the other, this is where the lockable trigger comes into play, Set your camera to say 30 seconds or what ever length of exposure you need or your camera can take in combination with aperture and ISO then set your trigger to the locked position, this will ensure that your camera will keep taking your specified exposure until you unlock the trigger...when you have done all of this one last thing to do is make sure that you've got all long exposure noise reduction switched off as this will slow your camera down and cause gaps in trails, additionally it will increase battery drain


Important Note

Don't forget you’re on a tripod so if you have it turn your Image Stabilization or Vibration reduction to the off position and switch to manual focus as you don't want the camera to try and find focus in the dark after each exposure, also make sure you have plenty of space on your memory card and fully charged batteries

Location...

...To get the best effect from star trails you want to try and get some interest into the foreground, as just a picture of star trails and be a little boring but this can be anything that inspires or interests you, it could be a building, a landscape even a car really anything you want...

Urban Star Trails

For detailed explanation on how to capture star trail in an urban environment please also checkout this fantastic guide to trails in urban areas written by Andrew (AndWhyNot) his guide can be found HERE

Straight or curved...

...You will notice with the two images above that the first has curves trails while the second has straight trails, this is caused by the section of sky that you have in frame when capturing your trails.

Due to the way that the earth rotates on it's axis if you can have the section of sky containing the pole star (Polaris) in frame or close to frame you will get the wonderful curved trails, to find Polaris the easiest way is to find The Big Dipper (The Plough) and this will lead you to Polaris

The software...

...there are a number of ways to go about layering your exposures to form a star trails but there are two brilliant and free pieces of software available to process your multiple images into a single stack image.

If you run Windows OS then two of the most popular are Startrails.exe and StarStax.exe both are available via a quick search on google, I will not put in the links in case they change over time 

If you are a Apple OS or Linux OS user then you cannot currently run Startrails.exe however StarStax.exe is cross platform so will run on almost all operating systems

A final thought...

...I hope that this has helped you and if you have any questions please don't hesitate to ask them and I shall endeavour to provide an answer

Happy Star Trailing