IMAGING
MATERIALS AND TOOLS
Digital camera Free gPhoto software supports
hundreds of cameras; check their website
( gphoto.org) to see if yours is on the list. Even
older digital cameras can take high-quality
pictures, and a 4-megapixel camera exceeds
the resolution required to make an HD movie.
Wide-angle conversion lens (optional) I want to
capture as much of the sky as possible, so
I bought a wide-angle conversion lens online
for about $30. It fits right over the camera’s
existing lens and doubles the angle of view.
AC adapter Don’t expect the USB connection from
your computer to supply power to your compact
digital camera! I found a cheap off-brand power
supply online that’s compatible with my camera.
PC A minimal installation of Linux, along with the
gPhoto software, will not place great demands
on your system; an old 600MHz Pentium III, for
example, has more than enough horsepower.
USB active extension cables (optional) I picked up
a couple for about $16 each. These can be daisy-chained together to reach distances of 60–80
feet (according to manufacturers’ claims).
Enclosure I used a 6"× 6"× 6" steel enclosure made by
Hoffman ( hoffmanonline.com), part #A6R66NK.
Picture frame glass for the enclosure window. My
local frame shop cut a 5"× 5" piece for a few bucks.
Slotted angle (optional) for mounting the enclosure.
I used two 6' lengths. The mounting hardware you
require may vary.
Miscellaneous hardware You’ll need a handful of
¼- 20 machine screws or hex bolts, washers, nuts,
and/or wing nuts, for putting it all together. If you
need to fit your camera with a power-on setscrew
(see Step 4), you’ll also need a 3" aluminum
mending brace, a 1" #8 machine screw, and a
couple of matching nuts.
Dremel or your favorite metal cutting tool to modify
the enclosure. There are many ways to cut sheet
metal, but I used a rotary tool with a tungsten
carbide cutting bit.
Silicone caulk
5-minute epoxy (optional) for attaching the setscrew
bracket (again, see Step 4)
Uninterruptible power supply, aka UPS (optional)
I want my system to survive short-term power
outages, so I purchased an inexpensive UPS
designed for desktop computers.
Software I used open source gPhoto software
( gphoto.org), which runs on Unix-Linux operating
systems. My flavor of choice is Ubuntu (ubuntu.
com), which is about as easy to install as Linux
gets. If you’re not quite ready to jump into the
Linux universe, there are great image capture and
time-lapse programs for other operating systems.
For Windows, there’s GBTimelapse shareware
( granitebaysoftware.com); it works only with
Canon cameras.
Pliers and vise-grips
120 Make: Volume 21
2. Install additional software.
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 line-command tools for manipulating
images, and Image::EXIF is a Perl module for
extracting EXIF data embedded in your image files.
3. Test your camera.
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.
4. Fix the power-up problem.
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
