How to take Star Trail images
Planning the image:
Firstly you need to decide how you want your final image to look, if you want the star trails to go around a single star you will need to locate Polaris (the Pole/North star) as this will stay central in the image and all other stars will appear to move around it. You can download free software called Stellarium from the Internet which is a brilliant Planetarium, and will show you the location of Polaris and has many other amazing features. You need to consider how dark your skies area, from our area around Manchester we have a lot of Light Pollution and it is worth planning you shot away from the glare.
The best way to make a star trails image it to take lots of images, one after another and then stack them all into one image using special software. The other option is to take a long exposure image but you would need to be in a dark sky site to do this and we have had no luck in our area doing it this way due to light pollution.
DSLR camera (so you can manually change the settings) but a decent point and shoot camera should work too
A tripod to keep the camera steady (for long exposure photography this is a must otherwise the image will be blurred)
http://www.startrails.de/html/software.html or http://www.tawbaware.com/imgstack.htm both of these are free and easy to use.
Things to check before heading out:
Battery is charged
Memory card is in the camera (yes, seems obvious but we have made this error before)!
That the Moon isn’t going to ruin your image
Now set the camera on the tripod and change the setting to Manual shooting.
The first thing you need to do is get a good focus. The best way to do this is to zoom right out with the lens to get a wide view (don’t forget to take automatic focus and flash off), point the camera at the brightest star you can see. Use the live view LCD screen as it is easier to see. Taking photos at night can be difficult as there isn’t much light coming into the camera but it’s easy when you know how! Hopefully now you should see the star on the screen, if you can’t see the star try increasing the ISO to around 1600 and the shutter speed to around 15seconds.
Once you have the star onscreen use the zoom button on the camera (on a Canon this is to the top right on the back of the camera body) and zoom in as much as you can on the star (don’t zoom in with the lens as you want to focus the camera without changing this). Once zoomed in you should them focus the star by manually turning the end of the lens, be careful not to turn the whole lens, just the end of it, holding the main body of the lens whilst doing this so it doesn't move can help.
Now use a compass if needed and locate the area in the Sky where you plan to take the shot, if you want to locate Polaris point the camera North.
Now you are focused in, take some test shots and get your settings right. You may have to change the settings a few times as every ones levels of light pollution will be different. Also keep in mind that if it hasn’t been dark for long, the higher exposure and shutter speed will give a rather bright image! So ..... Set ISO to about 800 and change the shutter speed to around 30 seconds. Take a test shot and view the results. If the image looks too bright reduce the ISO, if it is too dark increase it. You will need to adjust your exposure and ISO settings until you are happy with the image. If you don’t have a remote shutter release button, it can be a good idea to set a 2 second delay before a picture is taken, to avoid the camera wobbling when the shutter is released.
You are ready for the shots!
You need to take a lot of images, so it is best if you can set the camera off on an imaging run, so that it takes image after image for you, so you don’t have to stand there clicking the button every time! Make sure your memory card will hold hundreds of images! You should aim for well over an hours’ worth of images to see longer star trails, two hours and they should be brilliant! You should see some trails after around 30 mins though and these can still make great images. Be aware that you don’t want to leave long gaps between taking images otherwise there will be breaks in the star trails when you stack them.
Once you have all the images, transfer them off the memory card onto your computer. You then need to run your chosen software and use it to stack all the images into one single image. You will find help guides on both websites on how to do this.
You should now have you final image!
Good Luck and please don’t forget to share your images on the OLDHAM & ROCHDALE ASTRO FACEBOOK PAGE we would love to see them. Don’t hesitate to for any help on the Facebook page or on our COMMENTS PAGE, there are no stupid questions and we are a friendly bunch!