Making a Star Trails Time Lapse

Short tutorial about how I made this video using free software:

 

Taking pictures of the stars

Take lots of photos in manual mode with a long shutter speed (30-60 seconds) and intervals as short as possible. I used CHDK on an old Canon Powershot to shoot at intervals. Take a dark frame (by covering the lens with your hand for example) at the end; this can be used to subtract sensor noise.

Stack pictures

I used Python and PIL library to stack pictures on top of each other. The script I used can be found here. (I don't know if it still works). Put the .py file in the folder with the photos and run it. It can be slow.

Create video

You can use Virtual Dub to create an AVI file of the stacked photos.

Tutorial: Creating a timestamp on photos/timelapse

Draw a timestamp on your time-lapse

I think its nice to be able to see how much time has elapsed during a time-lapse video. To do this, a timestamp has to be drawn on each image. This can be done with batch processing in some photo editing software, but I did it using python scripts. Its free (apart from Windows) and more customizable. Here's a tutorial on how to do it.

Software requirements: Windows, Python, PIL, (Aggdraw)

To run python scripts, you need to have Python installed. To be able to draw on photos, you also need the Python Imaging Library (PIL) which is only available for Windows. For drawing a nice anti-aliased clock you also need Aggdraw. Make sure all packages have the same version number, eg. 2.6.

Script

Now you need a script which opens each photo, take the EXIF date/time information and draw it on the photo. Below are two scripts you can use. Save it as a .py file and put it in a folder with .jpg files. Click on the .py file and the script should run. Done! Your images are now saved in a new subfolder.