We’ve all seen time-lapse movies that seem to speed up the world around us. The effect is very compelling, making processes that normally occur at a rate too slow to perceive unfold before our eyes, such as the blooming of a flower.
I’m working on a time-lapse movie that captures the dynamics of weather and clouds, and the patterns of sunrise and sunset for an entire year. I need a setup to capture a large number of images. I need to collect these images without interrupting the image-capture process, and to access the system remotely. I want to do it on the cheap, without sacrificing quality.
Here’s the solution I came up with: I’m putting a dusty old PC back into service, installing Linux and gPhoto image capture software, and connecting it to my old 4-megapixel Canon A520 camera via USB. The camera will be mounted in an improvised (yet sturdy) outdoor enclosure. With this setup, the images can be continually captured directly to disk, around the clock, and I’m able to log in remotely to control the camera. I can also compile the images into movies on the same system.
Step #1: Install Linux.Next
- Note that installing Linux will wipe out any data on your PC. You can download the Ubuntu installer for free (http://ubuntu.com), or buy the DVD from Amazon.
- The installation tools will walk you through the entire process, asking you to select various application packages.
- You’ll likely want an OpenSSH server so you can remotely and securely log in, a web server such as Apache so you can view your images remotely, and any scripting languages you may find useful, such as Python or Perl.
Step #2: Install additional software.Next
- The easiest way to install software on Ubuntu is using its package manager system. To install gPhoto, log in and enter the command: sudo apt-get install gphoto2
- Likewise, you can install FFmpeg (which you’ll use to assemble your images into a movie) like so: sudo apt-get install ffmpeg
- It’s likely that you’ll want a video player to view your creation. For Linux, there is VLC: sudo apt-get install vlc
- You may also choose to install other programs or libraries. For example, ImageMagick includes a number of command-line tools for manipulating images, and Image::EXIF is a Perl module for extracting EXIF data embedded in your image files.
Step #3: Test your camera.Next
- Before putting your camera in its enclosure, see how it works with the software. Connect your camera to the PC with its USB cable, and power it on. Log into your Linux box and enter the command: gphoto2 --list-config
- GPhoto will attempt to auto-detect your camera. If successful, it will output a list of configuration parameters. For many supported cameras, you can manipulate all the camera’s settings just as if you were operating it by hand. For example, to set the image capture size to the lowest resolution: gphoto2 --set-config imgsize=small
- Some cameras may need to be identified explicitly, for example: gphoto2 --camera “Canon PowerShot A520 (PTP mode)” --port usb: --list-config
- Before capturing an image, Canon cameras must first extract the lens with the command: gphoto2 --set-config capture=on
- To capture 3 images at 10-second intervals, enter the command: gphoto2 -F 3 -I 10 --capture-image-and-download
- This will capture and download 3 image files into your current directory: capt0000.jpg, capt0001.jpg, and capt0002.jpg. If you have problems, the gPhoto site has good documentation.
Step #4: Fix the power-up problem.Next
- One problem I ran into with my Canon A520 was the fact that when its power supply is momentarily interrupted, restoring the power will not automatically turn the camera back on.
- Fortunately, I found that my camera will switch on upon power-up if its power button is held in the depressed position.
- To do this, I fashioned a simple bracket and setscrew. I bent a 3" aluminum mending brace as shown in the photos.
Step #5: Next
- Now thread one nut partway down the #8 screw, insert it in a bracket hole, and thread the other nut on the other side, so that it looks like the 1st photo.
- Then, positioning the screw directly over the power button, glue it in place with 5-minute epoxy as in the 2nd photo.
Step #6: Next
- Hold onto the nut between the brace and the camera, and turn the machine screw by hand until it begins to tighten against the power button.
- You should feel some resistance, and the camera should turn on. Don’t overtighten, as this could damage the camera. Tighten the top nut against the brace to lock the setscrew in place.
- Note that with the power button held down, you may not be able to operate the camera manually, as its buttons will be unresponsive. You will, however, be able to operate it remotely using the gPhoto software.
Step #7: Install the enclosure window.Next
- I removed the front cover of the enclosure, cut a 4"×4" window, and sealed the glass into place with the silicone adhesive.
Step #8: Assemble and installNext
- Camera tripod sockets accept a ¼-20 bolt, which makes it easy to improvise a mount with a single bolt, mounted through the floor of the enclosure. Use a hex nut to tighten a large washer against the bottom of the camera.
- I want my camera pitched upward within the enclosure, to capture more of the sky, so my mount includes an L-bracket bent down to about 45° using a couple of pairs of vise-grips.
- The camera is attached to the bracket using a ¼-20×1" machine screw, a big 1½" washer, and a nut. The other leg of the bracket is mounted to the enclosure floor.
- If your enclosure has knockouts, you may want to use them for bringing your power cords and USB cables into the box; I just cut a notch at the front of the box floor for easy access with the enclosure cover door removed.
Step #9: Put it all together.Next
- After assembling the enclosure outside, I plugged my PC and the extension cord into the UPS power supply, and ran the power and USB cables out my window.
- I made sure the setscrew was properly set to ensure that the power is on, then plugged in the AC adapter and stuffed it, along with anything else that might need protection from weather, inside the enclosure.
- Then I mounted the enclosure on my roof.
Step #10: Make time-lapse movies!
- Hopefully you’ve pointed your camera at something interesting. To capture an image every 10 seconds for 1 hour, log into your Linux box (or open a terminal window), and enter the following command: gphoto2 -F 360 -I 10 --capture-image
- When it completes, you’ll see that the current directory is filled with image files. Enter the command: ffmpeg -f image2 -i captd.jpg -sameq FirstMovie.mpg
- This will assemble the images into an MPEG movie file. To view it, open it with VLC: vlc FirstMovie.mpg
- At the default 24 frames per second, this gives you a whopping 15 seconds! Of course with this setup you’ll be able to make movies much longer than that. To tell gPhoto to run indefinitely until you interrupt it (using control-C), simply set the -F flag to 0: gphoto2 -F 0 -I 10 --capture-image
- This just scratches the surface. The gPhoto and FFmpeg programs are extremely powerful, and the possibilities are endless for creating beautiful time-lapse movies that span days, months, or even years.