ARDUINO CAMERA DETECTOR HOW TO
ARDUINO CAMERA DETECTOR DRIVER
ARDUINO CAMERA DETECTOR SOFTWARE

To take images, I used software that came with my Canon camera. Some nights it has taken me 15 minutes or more to get the target star framed. A right-angle viewfinder attachment ($20, used) makes that easier, but it’s still a challenge. I aim my camera by first eyeballing things and then walking the field of view from star to star. The trickiest step in the operation is getting the camera pointed at the target star.

The final component of the tracker is a ball head ($18 on Amazon) bolted to the top, which allows me to orient the camera in any direction. But I soon abandoned that as being too precarious and built a sturdy wooden platform. Initially, I mounted my tracker on a camera tripod.

ARDUINO CAMERA DETECTOR DRIVER

The stepper motor is controlled, via a driver board, by an Arduino microprocessor that lets me set the rate at which the doors separate. Rotating the nut pushes the doors of the tracker apart. To drive the tracker, I pulled some gears out of a defunct inkjet printer, attaching one gear to a stepper motor and the other to a nut screwed onto a gently curved length of threaded rod. Aligning the hinge to your hemisphere’s celestial pole allows you to track a star as the plywood “doors” separate at a constant rate. Instead I built a “barn door” tracker-essentially two pieces of plywood hinged together. I could have bought a commercial star tracker, but that would have put me back several hundred dollars.

ARDUINO CAMERA DETECTOR HOW TO

The next task was to figure out how to make the camera track a star during long exposures. With old manual-focus lenses now useless to most photographers, I was able to acquire a 300-millimeter Nikon telephoto lens on eBay for a song (US $92, shipped), along with a Nikon-to-Canon adapter ($17 from Amazon). So I decided to follow this lead and went shopping for a telephoto lens for my Canon EOS Rebel XS DSLR. (Astronomers, who use a logarithmic scale to describe the magnitude of a star’s brightness, would call that a 28-millimagnitude difference.)

It was the obvious choice because its parent star is relatively bright (although still invisible to the naked eye), and the star drops in apparent brightness during a transit by 2.6 percent, which is a lot as these things go. The exoplanet he chose to go after was a gas giant that belongs to a binary star system variously named HD 189733, HIP 98505, or V452 Vulpeculae, depending on the star catalog. He was able to discern the dip in the brightness of a star as an orbiting planet passed in front of it-a technique known as transit detection. I discovered that one amateur astronomer had already posted online about how he had detected a known exoplanet using a digital single-lens reflex (DSLR) camera outfitted with a telephoto lens. That got me wondering: Might I be able to detect an exoplanet without a telescope or a research-grade CCD detector? The project’s astronomers find exoplanets not with a giant telescope but by combining a charge-coupled-device (CCD) detector with a Mamiya-Sekor lens originally designed for high-end cameras. Then I stumbled on the website of the KELT-North project at Ohio State University, in Columbus. I knew that dedicated amateurs could detect some of these exoplanets, but I thought it required expensive telescopes. Since 1995, when astronomers announced the discovery of a planet orbiting the star 51 Pegasi, exoplanets-which orbit stars other than the sun-have been a hot topic.

Arduino camera detector