Time Lapsed Astrophotography

A few times I have tried to make time-lapsed videos of the stars moving across the night sky. I have always found this to be a mesmerizing thing to watch in a time-lapsed video. The process is not very hard, just time-consuming.

The first step is to find a truly dark place to be on a moonless night, ideally. This is because the stars are so dim, you need a long exposure to capture many of them and any other light source like the moon or light pollution will overwhelm the stars and they won’t show up well. West of Austin, there is a place called Canyon of the Eagles park and the Austin Astronomical Society uses the place for telescope viewing. So, I have been out there a few times and it is pretty dark on a moonless night. It is right on Lake Buchanan so you may get to experience mosquitos as well as stars.

The next thing you will need is a camera and tripod and a chair to sit in while you wait. I wanted a wide lens for this to capture as much of the sky as possible as this will make it more dramatic. If you point the camera to the West or East, you will see the stars and Milky Way rise or set as the Earth turns. If you point North, you will see the stars rotate about the North Star (Polaris). In this case, I wanted to see if I could get the Milky Way moving across the sky. See the video that I made and posted on Vimeo below:

Stars October 10, 2015 from Jason Frels on Vimeo.

The camera is pointing at the Southwestern horizon, over the lake. The light in the sky on the distant horizon is from the city of Llano several miles away. You can watch the Milky Way slowly move to the right. You also get airplanes, meteors, satellites, UFOs, etc., which I don’t mind. A short video, but a lot of work.

To set up the camera:

  • Put the camera on the tripod and point it in the direction you want. Take a few test shots to gage the focus and exposure. Focus can be a bit tough with such a dim subject.
  • Configured the camera for long exposure noise reduction as this improves the image quality quite a bit.
  • I also set the camera to only produce JPEGs and not RAW images to avoid filling up the memory card with large RAW files. The movies is stitched together from the JPEGs anyway and I wasn’t going to process hundreds of RAW files into JPEGs on the computer, so I let the camera do it.
  • Next, set the camera to automatically take pictures at specific intervals. In the Nikon D5300, there is a setting in the Shooting menu for Interval timer shooting. Using this, you can configure the camera for a specific number of photos at a specific interval.
    • Keep in mind that with noise reduction, you will have to account for more than twice the exposure time between shots as the camera takes a second picture with the shutter closed to subtract noise from the first picture. So, with 20 second exposures, I may set the interval to 50 seconds.
  • To avoid a jumpy or stuttered look on video, you will need to plan for about 24 frames per second. So, take 240 frames, get a 10 second video. The limit on the number of frames you can take will be your memory card, battery, or patience.

As soon as you start the shooting, you just need to sit and leave your camera alone while it does the work. Bring a chair and something to do.

To stitch the movies together I used Microsoft Movie Maker, which is a free app. You can download it, but I don’t know how much longer it will be supported. It is easy to use and produces a decent video and it is free. I learned pretty quickly to back up all of my images that took so long to take in the middle of the night. If the software corrupts the images, you are done, and this happened to me.

The procedure is to load Movie Maker and open up all of the JPEGs. The files should be in order as the camera names them numerically. Next, set the delay to the fraction of a second that you want; 0.04167 seconds per image for a 24 frames per second rate. You can also add text or music if you like. You can preview the movie or export it to a movie file, which can take a few minutes. Then you’re done!

Another place I went to try this was Colorado Bend State Park, which is way out West of Austin and nicely dark on a moonless night. I did this in January and it was well below freezing that night. I thought that since it was so cold, the clouds and humidity would not be a problem and I would get a nice movie. But, in January there is not much Milky Way to be seen, just lots of stars. See the video below.

CBSP 010916 from Jason Frels on Vimeo.

It was very dark out there; notice how little light pollution is on the horizon. I could not even see the ground and I was freezing, but I managed to get the camera set up and then went and sat in the car and read a book, periodically turning the engine on to get some heat. Living in Central Texas, I am just not that well equipped for a cold night and that was about as cold as we get here.

I think that this video turned out much better as the clouds rolled out and all the stars came out. You can also watch the Andromeda galaxy set in the West, which I really like.

I am thinking about trying this again in September to get a really nice view of the Milky Way, which just amazes me when I think of the billions and billions of stars of the galaxy that we are seeing from within. It is hard to believe how small we really are.

3 Comments

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  1. Ramping up your game since I last stopped by – well done.

    Like

  2. Very cool. I went out one night to just try a picture of the sky. There was thousands of stars that were not visible to me by eye .

    Liked by 1 person

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