Shooting the Night Sky

The most common photographic subjects in the night sky, other than the Moon, are the Milky Way, and Star trails.

Shooting the Milky Way

When you photograph the Milky Way you are shooting a type of image called "star points". Most of the discussion below applies both to shooting star points, and shooting the Milky Way.


Star trails

Shooting star trails is very similar to shooting star points. Because of the earth's rotation, each hour the stars in the night sky move by 15 degrees. In practice this means you'll need to have the shutter open for at least an hour to get a good star trail picture. If there is a full moon in the sky (or even a quarter moon) leaving the shutter open this long will result in most of the stars being washed out. So a work around was developed: when the Moon is out, leave the shutter open for at most 30 seconds and then immediately take another exposure. Repeat for at least the next hour or so. Over an hour you would get 120 exposures.

There are many programs on the web that can then be used to combine the pictures into a single image, or even a video. The programs all work in the same way: they layer the images and combine them so as to always take the brighter pixels from each image in the result. I use the program StarStaX which is freeware and can be downloaded here . This program takes as input a collection of either jpg or tiff files. I use tiffs. I shoot in raw mode, and then adjust the exposures uniformly to get as many stars as possible in the image. Finally I convert the raw files to tiffs and input them in StarStaX. When using StarStaX set the blending mode to Gap filling using Edit Preferences. If you've shot a dark frame check "Subtract Dark Images" as well.

In the northern hemisphere star trails are best shot to the north. This generates very nice circles about the North Star which can be viewed as an extension of the Earth's axis. Shooting to the east or west will generate long arcs, and shooting to the south (which should be generally avoided) will generate flat lines or very wide arcs.

The North Star always points to true north, as opposed to compasses which point to magnetic north. To shoot effective star trails you need to be able to find the North Star. First locate the Big Dipper which most people can easily do. Then extend the outer edge of the dipper as follows:

Locating the North Star

The brightest star in the Little Dipper is the North Star.

When shooting star trails use similar rules as for shooting star points: shoot wide (24mm or wider if possible), f/2.8 or faster, and ISO 400 and 30 seconds maximum exposure if the Moon is out. Shoot for at least an hour beginning at least 60 minutes after sunset and ending at least 60 minutes before sunrise. Shoot in continuous mode, or use a remote timer to get the necessary exposures. Test focus and exposure carefully before beginning your series.

Shooting towards the north produces the best star trails. Good subjects include the north entrance to The Wave, The Second Wave, Sand Cove, The Hooters, and Fatali's Boneyard, all of which are best shot to the north or northwest! The Temples of the Sun and Moon in Capitol Reef are also good subjects. Here is a sample image; the Temple of the Moon is in the foreground.

Capitol Reef


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