Summer has it’s share of astronomical beauties, and one of the most notable summer sights is the Milky Way Galaxy. As most people know, we reside in the Milky Way. The Milky Way is a Barred Spiral Galaxy; it has spiral “arms”. As we look up and see the Milky Way, we are seeing one of the arms of it. It has been visible for a while now, but it is rising earlier and earlier, making it more convenient to observe. Right now, it is visible after 10 P.M. Central time. It looks like a fuzzy band spanning across the sky. The Milky Way is home to many DSO objects; a good pair of binoculars will show wondrous view.
The Milky Way also provides some great photography opportunities. If you own a dSLR and a reasonably good tripod, you can take photographs of the Milky Way. Use your shortest focal length lens, as star trailing is more apparent with higher FL; higher magnification exaggerates the earth’s movement. Fiddle with your camera’s ISO to find a good balance between sensitivity and noise. My Nikon D3100 works great at ISO 3200; any other dSLR with similar APS-C sized sensor should be similar. Here’s a tip: turn of your camera’s noise reduction function (if you don’t know how to do this, consult your manual), it saves precious time. What the noise reduction function actually does is take another identically-exposed image after you have taken your shot, except with the shutter closed. So if you take a 30 second exposure, than it will take another 30 second exposure with the shutter closed. Then it subtracts it from your shot; you can subtract you own “dark frames” later in post processing.
On a tripod, you are usually limited to under 30 second of exposure. After that, you’ll need some sort of tracking to prevent trailing. What I like to do is “piggyback” my camera on top of my scope (which is on an uncomputerized, unmotorized german equatorial mount) and track the sky by hand. In the image below, (camera in bulb setting and using remote shutter release cable) the exposure is 288 seconds, or almost 5 minutes (4.8 minutes) of exposure with no trailing (288 seconds is my record, by the way)!
Of course, my tracking isn’t perfect, so there is an alternative: stack images. If you piggyback your camera on a scope, you can take multiple 30 second exposures and stack them in a post-processing program. If you’re handy with Photoshop, it can be done there. But for the image below, I used StarStaX, which is actually a program for star trails, but it worked on the image below, a stack of 111 and 229 second exposures, a total of 5.6 minutes of exposure.
Enjoy the Milky Way!