Comet Machholz, Part 2

Comet Machholz
I was inspired by this blog entry to go out and take my own photos of Comet Machholz.

We’ve been fortunate to have some clear skies the past couple nights. The guy in the article mounted his digital SLR on a telescope that was tracking the stars to prevent star trails and blurring. My only telescope is a tiny Tasco from my childhood with a flimsy equitorial mount, so I decided just to put the camera on a regular tripod and live with the trails.

I tried my Digital Rebel with both my 100mm f/2.8 lens and 100-400mm f/4.5-5.6 zoom. The zoom lens was easy to focus and handy for getting in close, but the slow aperture required longer exposures. The stars noticeably move in a few seconds when you’re zoomed in, and my images all had small star trails.

I had some trouble focusing the 100mm lens. It seemed that I had to just bump the focus over from what I would call “infinity” to sharpen the stars. Once I did that it was nice to use the wide aperture for shorter exposures.

I took lots of shots at varying ISOs and shutter speeds with both lenses. My best shot is included here (click the thumbnail), and was taken with the 100mm lens at f/2.8, ISO 3200, for 11 seconds. It shows both the green ball of the comet on the right and the Pleiades cluster on the left, and has the shortest star trails. This photo is unretouched except for some cropping…I need to learn how to work on astrophotos in Photoshop.

At some point I’d like to get a decent telescope and mount the camera on it, or at least build a barn-door tracker. Then I’ll be able to try better noise reduction and image stacking techniques.