Star Trails and Other Night Photography

In mid-January, mild temperatures and clear skies combined to create fairly ideal conditions for some more night photography in Canmore. It was also the weekend right after the first full moon of 2014, so we had to take that into consideration when planning. How? First, we gave preference to subjects where we could be sure the moon would be behind us or screened by trees or mountains; this included going out for a long walk earlier in the day to seek out a new location that would minimize the impact of bright moonlight. Second, we headed outside as soon at it seemed fairly dark, so that we could get create an (at least) hour-long series of exposures before scheduled moonrise.

While planning definitely helped, we still had some failures of execution. The first night we went out, I set up two cameras: one to photograph star trails over the Three Sisters and one to photograph star trails over the trees growing down the northeast flank of “Little Sister”. As expected, set-up was a little time-consuming and included some trial and error before I was satisfied with the composition and exposure triangle for the first camera, which I set to take 120 exposures of 20 seconds each. I used the Startrails app to stack the individual jpgs. The resulting photograph reveals the equatorial plane: the invisible “line” along which star trails are straight, while star trails on either side are curved (in opposite directions). Most of the exposures were made before the moon rose, so there are just a few “moonbeams” visible at the left.

startrail-equatorial-plane

That first night, my second camera set-up was a wash. The resulting startrails were actually OK, but I didn’t take enough time with the composition and ended up with a really busy, unattractive foreground. It really is worth bumping up the ISO and taking a long enough exposure to reveal considerable foreground detail before finalizing your exposure triangle and starting your sequence of exposures. I wasted more than 100 photographs and about 45 minutes of my life simply because I was rushing!

Meanwhile, Mr. GeoK turned his camera a bit more to the west, including Miner’s Peak, Ha Ling and most of Mount Rundle in his composition. Again, I used the Startrails app to stack the 85 exposures he took over about a 30 minute period. I’ve noticed that he tends to set his exposure triangle to allow more light to reach the sensor than I typically do; next time we’re out at night I think I’ll bump mine up a little.

Startrail-Mount-Rundle

The second night, we left the house before it was fully dark so that we’d have a window of more than 2 hours before the still-almost-full moon came up. Unfortunately, after the first two cameras were in position and running, the wind really picked up. Despite weights hanging from the tripods, the strongest gusts rocked the cameras enough that the stacked images are not at all sharp – more images in the digital recycling bin!

I set up our third camera after the wind started blowing, so my primary consideration became finding a location sheltered from the wind. In the end, we positioned the camera in a small depression in the middle of a small clearing in a stand of aspen. The lens pointed straight up at the sky and I’m relatively pleased with the result. Of course, the branches framing the top of the clearing were dancing in the wind, so they appear more delicate than the reality. And while I like the strong curve of the star trails, I would have liked it even more if I’d been in just the right location to include Polaris in the frame.

Overhead-startrail

Once we realized the wind had played havoc with our long series of exposures, we walked a little further east to create a few more conventional night photographs, mostly single exposures. Here are our favourites, including one 15-minute star trail:

Tree-and-starsInspired by my results of a couple of weeks ago, I aimed up the trunk of a large spruce. While I like the way a particularly bright cluster of stars can been seen through a break in the branches, I will limit future similar shots to either deciduous trees or coniferous trees where the branches start much higher up the trunk.

Short-startrailIt took just 30 x 30 second exposures to create this image. Although the star trails are relatively short, they are also quite bright and there is added interest from the three planes that crossed the frame during that same 15 minute interval. There is also a bit of a glow in the lower left – light pollution reflecting off low-lying cloud.

Stars-spruceMr. GeoK took a single photograph of the pair of spruce trees. Despite the relatively short exposure (40 seconds), very short star trails are still visible. As a result, we went off to the interweb to learn about how to take night photographs without too much “noise” and without any star trail and discovered the “500 Rule“. And remember – if you’re using a MFT format camera, you’ll have to adjust the focal length by a factor of 1.5.

The “500 Rule” is one of a growing list of things I’ve written into the little notebook I carry in my camera bag. A few more night photography outings and I think I’ll be ready to share my list of things to know if you’re just getting started with star trail photography. If you have any burning questions or a personal “must do” step for night photography, please leave a comment and I’ll respond in an upcoming post.

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One thought on “Star Trails and Other Night Photography

  1. Pingback: Photo Blogging Challenge – Two (March 2015) | Out and About with the GeoKs

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