Earlier this month, I spent a significant amount of time in Las Vegas for work. It was an incredibly busy week, but I still managed to find a couple of opportunities to run out to Valley Of Fire State Park to do a little shooting. I spent most of the time shooting stars for time lapse. I managed to get in a few sequences, and I'm really pleased with how they turned out. I'll get them completed and into a video in the next few weeks. Normally with time lapse, you shoot with an interval of 1-5 (or more) seconds between each shot. This allows you to really compress time. With stars, you typically get better results if you lock down the shutter and let the camera crank out frame after frame. The beauty of this method is that you can also use the frames to stack for some star trails. Nothing better than a BOGO, right? If the frames were shot with any kind of an interval greater than the length of the shutter being open, you'd end up with blank spots in your trails. Not good. So, after rendering the video from one set of shots, I decided I'd do some stacking using my typical process (more on that later). As I had expected, the results were fantastic. Then, a suggestion from a friend prompted me to try a different method. The results were good, but there was an added bonus that really made the new method worth while. Not too shabby, two BOGOs off of the same sequence! It's like a BOGOGO.
So, for starters, here's a single frame from the sequence. You can see that getting out away from the Vegas lights was well worth it. It also helped that we were only a few days away from a new moon so there was very little ambient light. Actually, some ambient light would have lit up the crazy red rocks. The streaks you see in this and other images are the result of air traffic headed to Vegas.
This first video clip is the rendered time lapse sequence. This is made up of 438 images, each 15 second exposures, captured over a total of 2 hours. I'm very pleased with the results, can't wait to get it in with the others and add some music.
Alright, now that the time lapse was completed, it was time to build a stacked star trail image. I frequently get asked why I prefer to stack rather than shoot one long image. Well, there are several reasons. First, stacking multiple short exposures greatly reduces the amount of noise and hot pixels that you get in your image. Second, if needed, you can drop a couple of frames. Be careful with this because you start to introduce gaps in the trails. Third, it's usually a lot easier to dial in your exposure. It's far easier to shoot a 15 second frame, adjust, shoot a second frame, adjust, etc. than it is to shoot a 2 hour frame and then have to make corrections and shoot again. The first step was to export the files as .jpgs. You can do it with RAW images, but it will really tax your system. With all of the images in a folder by themselves, I use a Photoshop action from starcircleacademy.com. This is a handy tool that does a great job of stacking. This is the image, straight out of CS5 with no final tweaking.
My friend Ben made the suggestion that I give a program called StarStax a try. I figured it was worth a shot, so I downloaded and installed the program and gave it a try with the the same images as a comparison. On the first run, I tried the "Gap Filling" option. On these images, the results weren't fantastic. I think it muddied the trails too much. I can see that with the right set of images, it would be useful.
So, I wanted to give it a fair test, so I ran the stack again, this time using the standard "Lighten" setting. This time, the results were much better though I don't think there's too much difference between this and image rendered using the starcircleacadamy.com action. Again, these are straight out of the StarStax software with no final tweaking.
Really, I couldn't see a reason to use one over the other, until I realized that StarStax has a really cool feature. You can tell the software to capture and save an image after each stacking cycle. Turns out that the resulting images from this feature make for a really great time lapse.
This last image is a repeat of the first stack from CS5 with some final tweaks in Lightroom.