This past Friday my neighbor and I travelled to Long Beach Island (LBI) to try our hand at some astrophotography. I’d dabbled a bit during a recent pastor’s retreat, and wanted to get back to do a better job taking my exposures. LBI is a little over an hour away from where we live, so it didn’t take us very long to get on to the island. We then drove north to Harvey Cedars, where I knew there were fewer occupied houses. We found an ideal block and ascended the dune path to set up our equipment. The sky was stunning, but we did have one house that was lit up with floodlights, and that blew out a rather large portion of the sky. If I did this all over again, I would have continued to check for a block which had no illuminated houses. They are terrible–and during the summer, when the island is full, I can’t imagine these sorts of photos would be possible.
I set up my tripod and camera and proceeded to take forty exposures of the same scene, which I planned to feed to Starry Sky Landscape Stacker. This application creates composite of these many exposures into single image which uses more light. Through this experience I’ve learned some things.
First, I need to pay attention to my exposure meter when I’m taking my exposures. A high ISO and long shutter speed are essential for capturing decent exposures, but given the presence of the floodlit house I should have lowered some of my settings. I was taking 30 second exposures, and I probably needed to set it to 25 seconds.
Second, spill light is the enemy. The aforementioned house did make for a nifty effect, but only after some agonizing work I’d rather have not needed to perform. My friend Jamison even pointed out I could have trigged my camera timer from my phone, which would have given me a chance to put it to sleep. The light from the screens on the camera itself is also detrimental. Turning off the external screen is easy enough, but I need to find a way to block the screen on the eyepiece. These are things which I’ll be exploring moving forward. On the other hand, a few exposures where I illuminate the foreground with a flashlight 1 can make things look more interesting in the final composite.
Third, Youtube tutorials are great, but reading an application’s own documentation can be an immense help. My first attempts with Starry Sky I processed my images according to a tutorial, and got mediocre results because my photos were blown out from the start 2. After reading Starry Sky’s own guide, however, I figured out that even my minimal processing was too much. My photos were already the ideal for what Starry Sky needed, so my tweaks were not helpful–with one exception, that is. One particular tip Starry Sky gave me was to make sure the white balance values were the same on every exposure. I couldn’t assume that they would be the same off camera, or even using On1’s auto white balance. Instead, I took a nod from the developers and set my white balance to “custom” and copied those values to each exposure. I’d have never figured that out that trick on my own, and it made a huge difference in the final composite. I now understand a bit more of what Starry Sky is doing, and it makes a big difference.
The composite image below is 19 exposures of of the sky, plus one exposure with my lens cap on using the same settings 3. The dark exposure is used as a reference for sensor noise by Starry Sky, which helps to separate sensor dots from the stars. My ISO was set to 6400, and I was using a 7.5mm fisheye with an aperture of ƒ/2.8. Each exposure was 30 seconds and, as I mentioned above, I’ll probably drop that to 25 when I go back. The composite exposure was then brought back into On1 Photo Raw, where the tones were corrected for a more natural-looking image. I also used a feathered clarity brush to bring out a bit of the Milky Way. My poor camera couldn’t get it to come out in all it’s glory with the light-pollution I had around me, but it’s still visible 4.
All told, this was a wonderful experience, and I’m still playing with my exposures to see what I can produce.