Star Trails and Astrophotography with Lumix GX1
During the 2013 Persieds Meteor shower, I took my camera to Lake Solano near Winters, CA. Using Blue Marble's nightlights 2012, I searched for the darkest skies in Solano County and found Lake Solano to be a reasonable driving distance away. I've never shot stars before, and after some Googling I wasn't too sure my camera was up to the task. Nonetheless, I drove out and set up my camera along the shore.
I cranked up the ISO to 1000, shutter speed of 30 seconds, and f/3.5. Long Exposure Noise Reduction (LENR) was turned off in camera to continuously shoot. Manual focusing in the dark was hit or miss. I tried using an LED flashlight on the trees to focus, but the magnification on screen didn't help much or rather, it hindered. I connected the intervalometer and set it up to fire continuously. After a couple hours I came home with a little over 200 photos.
I shot in RAW, as a kind of safety net. The flexibility of RAW to make post processing changes is well known and the uncertainty of image quality necessitated the format. With RAW, the workflow for a time lapse is increased greatly. I denoised in Aperture, though not in Topaz Denoise. I could apply denoising to one photo in Aperture and apply to all the photos in the set, but with Topaz I would have to denoise each photo individually. I'm unsure if Topaz has batch editing or not, nor was I interested in Topaz making 70MB TIFF files multiplied by 200+. I did, of course take a dark frame with the lens cap on to pattern match the hot pixels since I turned LENR off. I exported jpegs to a folder and ran the photos through StarStaX.
StarStaX is an app to process star trails and has some nifty options. Most importantly it has Dark Frame Subtraction so I can use the shots with the lens cap on to pattern match the hot pixels. I chose cumulitive image saving and comet mode to create the above time lapse. I ran the images into Time Lapse Assembler for Mac to make the clips and edited the clips in iMovie.