I wanted to get used to using some freeware called Startrails (believe it or not!!!) I found it while researching star trails astrophotography, and it is GREAT! Simply, it acts much like regular astro image stacking software. But what it does is place each individual frame on top of each other using the entire frame as a reference, not the stars themselves. The advantage of this is that if you live in a light-polluted area (which, sadly, most of us do!) you can take short exposures and then stack them using this software to create a final star trails image. For practice over recent nights, I was able to use 30 second exposures to generate decent image issues once stacked. This was with neighbors' houses well-lit and a light dome from a nearby toll booth station! The software is also REALLY easy to use. Simply point it to the directory/files which are in effect your light frames, (optionally) point it to your dark files, and click on the "Startrails" button in the application and it processes the image for you. It will even produce an .AVI movie of your shots which illustrates the movement of the stars around the polar region quite nicely (depending on your raw shot quality, of course!!!) Anyway, the link to the software is here.
Tonight, after some heavy clouds, the skies suddenly cleared and I drove about 20 miles north of home, to a dark highway turnoff. I took about 35 minutes worth of images before unexpected fog hindered my ability to take additional snapshots. Below is the image resulting from these shots and the use of the Startrails software.
- Nikon D40
- 18mm lens setting @ F5.6
- 35 * 1 minute exposures
- Stacked in Startrails
Not a bad image, really. You might be able to point out Cassiopeia to the left, and Ursa Major to the right!
Next time I will try for somewhere between one and two hours. Anyway, get the software and give this a try! For those folks without scopes but with DSLRs and a decent tripod, this software allows you to easily obtain nifty looking star trails images.