Star Trails

Every summer at early-mid August, we enter a portion of the solar system rife with meteors, and ever year around this time, many of those chunks of rock and debris hit our atmosphere and burn up, giving us the Perseoid meteor shower. This year, the shower did not occur during a full moon, and so the skies were dark and the stars were bright.

Some of the photo club folks wanted to have a camping trip this weekend, and that devolved into a fire and star photography night at our place. The meteor shower was pretty good Saturday night. There have been lots of big meteors that leave trails that hang around for seconds after the main chunk had burned up. And they came quite often. If you stared at any one part of the sky, you were bound to see one within 20 minutes.

The star photography was so-so, at least for me. Its the same view from my back yard every time, so I’d like a change of foreground. I’m also stuck with the same problems every time: I need a wide lens that can open up wider than f/2.8, and I need a camera with useable image quality at high ISO’s (faster than iso 1600). So until I have that combination, I’m not likely to get any clearer images of the sky than I have previously.

I did experiment with long exposure star trails. I left the shutter open for over an hour which pretty much killed a fresh battery. The problem with long exposures and digital cameras is that the sensor heats up leading to extra noise in the image. This is where film photography has the advantage. Plus, older film cameras don’t even consume battery while the shutter is open, so you can expose an image all night if desired.

I think one hour is my limit with my current set up. The better option is to stack a series of shorter images which has the added advantage of cancelling out the random noise. However, and intervelometer is necessary to pull off a series of 30-second or 1-minute back-to-back exposures. So, I will continue to work within my limitations while admiring the images from those with more capability. In the mean time, here is my 67 minute exposure. Each star trail should be about 1/24th of a full circle, or an arc angle of about \frac{\pi}{12}.