With a view like this from my room I couldn’t resist trying some star trails. I also learned a bit about astronomy from this picture. I was expecting all the stars to arc in the same direction but because of the ultra wide angle lens, I captured the celestial equator in the middle of the frame.
Just a few years ago this was truly an art, knowing precisely how to expose a single exposure to get star trails. With today’s DSLR’s it’s much easier to get a good image. This image is made up of approximately 150 images by using a series of much shorter timed exposures then combining all the images in Photoshop.
Getting the images is straight forward, the key to this is using the right tool to combine all the imgaes into a single image. Russell Brown from Adobe has written a script called Stack-A-Matic that makes this a no-brainer. You can download it from here, Dr Brown Scripts. Simply install the script into Photoshop, in my case I’m running CS5 Extended, select all your images in Adobe Bridge, launch the script from the Tools menu in Bridge and wait. Just above the download link for the script Russell has included a video on how to use it.
There are a couple of options you have when you launch the script, I choose the option to have each layer created with a layer mask. Over the course of the night, there were a few cars that drove through the frame that I was able to eliminate on the individual image on which they appeared. To me that was a cleaner solution than doing a global change on the images after all the layers had been flattened. It was strictly a personal preference but I thought the images was stronger without the headlight trails.
Image captured with a Nikon D3s, Nikkor 14-24f2.8 AFS, Nikon MC-36 Multi-Function Remote Cord, EH-6A AC power adapter, Gitzo 3541XLS tripod with a RRS BH-55 ballhead.