Barn-Door Tracker The Summer Triangle This is a wide-angle 2.5-minute exposure taken with a very simple, homemade, barn-door tracker. The most important basics of fixed-tripod astrophotography are employed here: accurate focus and correct exposure. Tracking the stars to compensate for the Earth's rotation allows for much longer exposures that record fainter stars, and even the Milky Way from a dark-sky observing site.

This shot is of the Summer Triangle. It was made with the camera on a hand-driven barn-door tracker.

Brilliant Vega in Lyra is at the top of the frame. Deneb in Cygnus is at lower left. Altair in Aquila is at lower right.

The rich star clouds and dark nebulas of the Milky Way in Cygnus dominate the image. The Great Rift runs through the star clouds above Aquila through Cygnus in the center of the frame. Le Gentil 3, a large dark nebula, is to the left of Deneb.

The image is a 2.5 minute exposure at ISO 1600 at f/3.5 at 18mm of focal length. A fog filter was used to make the bright stars more easy to see.

During the exposure, while my head was down and I was concentrating on turning the drive bolt at one revolution per minute, a satellite passed through the frame, flaring as it went past Deneb.

Image Data

• Lens / Scope: Canon 18-55mm f/3.5-5.6 EF-S Zoom IS lens
• Focal Length: 18mm
• F/stop: f/3.5
• Exposure: Single 2.5-minute exposure
• Mount: Barn-Door tracker
• Guiding: None
• Camera: Unmodified Canon EOS 1000D (Digital Rebel XS)
• Mode: JPEG
• ISO: 1600
• White Balance: Custom, set on sky background
• In-Camera Noise Reduction: Off
• Filter: Tiffen Double Fog 3
• Temp: 40F
• Start Time: 3:46 a.m.
• Date: May 19, 2009
• Location: Maxwell, NJ
• Calibration: None
• Processing: Standard in-camera JPEG processing. Color adjusted a bit in post processing.