![]() ![]() So you might consider a preference for long-held film best practices to be "traditionalist" thinking as well. Since the photographic industry honors the achievements and traditions established over many decades, photographers who learned on film still dominate the industry in many ways. Some purists believe that everything should be captured in one exposure. In the old film days, star trails were accomplished by leaving a camera shutter open for one long exposure, even for many hours. Yosemite is under a major flight path for airplanes StarStaX allows you to identify these images so it can automatically eliminate those hot pixels. The only data in the image should be the hot pixels. At the end of your star trails sequence, put your lens cap on and take a few more images of the all-black capped lens at the same settings you've been using. If you're shooting on a relatively warm night, about 60 to 70 degrees or warmer, with many cameras you may start to see more hot pixels the warmer it gets. In very long exposures, digital camera sensors can produce random spots of bright single pixels referred to as "hot pixels". I used the free StarStaX software (in "lighten" mode, where the lightest pixels are kept as images are merged, creating the trails as the stars move from frame to frame. Leave as little time as possible between shots.įor this example I used about 80 shots of 30 seconds each, covering 40 minutes. Once you have the basic exposure figured out, take that exposure over and over until you reach 30 to 45 minutes or more total. The main exposure of 15 seconds enables me to quickly use Automatic Exposure Bracketing to take lighter and darker exposures at 30 and 8 seconds to verify the best exposure setting, then I can pick an equivalent exposure at the camera's longest internally available setting (currently 30 seconds on most cameras). Take lighter and darker shots to ensure that you've identified an exposure which isn't too bright or too dark, then set up your camera to capture a sequence of images at the optimal settings. On a darker night you can choose a wider aperture, higher ISO, or increase your exposure time using an external intervalometer. If you'd prefer to drop your ISO to 1600, simple double the shutter speed for the same overall exposure. ![]() Under a bright full moon in clear skies I might start at f/4 at ISO 3200 for 15 seconds. Cameras have slightly different sensitivity to light, and the moon brightness (phase) and local light pollution can affect your exposure from night to night, so you'll need to run some tests to determine what settings to use for your individual shots.įull moon exposure: 15 seconds f/4, ISO 3200 You'll also want a consistent exposure, so use your camera in Manual exposure mode. You'll want to take sequential shots close together so the star trails to be continuous, so turn off your camera's long exposure noise reduction. The focus ring of your lens probably continues past that point to compensate for differences as temperatures fluctuate, so focus during daylight on a distant object and note where this is, or if your lens has continuous focus ring with no visible scale, focus your camera during the day, switch it into manual, and carefully tape the focus ring with removable painter's masking tape or gaffer's tape. You'll need to focus your lens on an object at close to infinity, and leave the focus mode set to manual so it won't hunt for focus in the dark. Ideally you'll have a remote trigger that can lock down to fire off sequential shots, or even better, an intervalometer which takes shots at certain intervals which you define. You can trigger exposures manually, but that's tedious and not fun to do for an hour at night. You'll need to capture images covering 30 to 60 minutes or more. As is often the case, the challenges come in the details. At the highest level, all you do is run a sequence of night star shots through a star trails program and enjoy the result. With today's digital cameras it is surprisingly easy to create star trails images. Yosemite Star Trail Reflection, originally uploaded by Jeffrey Sullivan.
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