Star Trails at Oregon Star Party
Description: Here are some star trails over the Oregon Star Party. The image was taken on August 26, 2008. I wanted to try something different from deep sky astrophotography, so I set my Canon 20D DSLR up on a standard camera tripod to get some star trails. I've only done star trails once before and since the camera was pointed fairly high, I found them kind of boring. To make this shot more interesting, I included the camp sites across the field from my observing site.
Equipment: The image was taken with a Canon 20D on a standard camera tripod.
Exposures: 1 shot just before dark to capture the tree line and clouds, 50x180 second shots to capture star trails, 5 dark frames. All images taken at ISO400 and saved as RAW.
Processing: The 5 dark frames were median combined in Maxim/DL into a master dark. In Photoshop CS2, I subtracted the master dark from each of the 50 star trail exposures as a difference layer. I then combined the tree line shot and 50 star trails shots as layers using the Lighten blend mode. Finally, I selected a few of the clouds from the tree line image and pasted them over the star trails using heavy feathering to get the trails behind the heavier clouds.
Click on image for full resolution.