An eight hour time-lapse of 240 two-minute exposures, stacked.
Creating a star trail photo sounds easy at first blush: Just set the camera on a tripod and keep the shutter open for a few hours. Right? That will work, but the settings required are critical. As they say, the devil is in the details. I experimented with different settings and chose to go with 2 minute exposures for each photo knowing that I could “stack” them in StarStaX for a composite shot.
My SONY RX100-IV is quite accomplished at gathering light. It has a superior sensor and a fast f1.8 lens. I chose settings that resolved dim stars yet kept the bright light pollution skies (Bortle 8) from overexposing each image: aperture: f/4.0 and ISO 80. My stars were crisp and noise was remarkably modest considering the sensor was working non-stop for 8 hours.
For processing the raw images out of the camera I use a Lightroom alternative called darktable. For editing the final composite I use Affinity Photo. (Yes, I’m an Adobe-free studio.)
There is a great deal of luck in making a successful star trail image because clouds and flying objects moving through the scene can ruin a whole night of shooting. Keeping the exposures to 2 minutes can allow for removal of a frame or two if they become spoiled and the resulting gaps can be smoothed over in post. In this project two very bright jet trails were removed. In post, I modified levels and boosted color saturation. The heavy lifting was done while developing in darktable for lens correction, removal of hot sensor spots, setting base curve and temperature.
One final tip that goes without saying (but needs to be said) the camera must not move AT ALL. On the previous night, a series of photos were marred by the tripod slipping a tiny fraction of an inch and misaligning every trail. A sturdy, trustworthy tripod is critical to success.
Give star trail photos a try! You may discover they are quite a lot of fun to plan and execute.
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