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Genres in practice3 min read

LESSON 38

Night and astro

Long exposures, dark skies, steady tripods.

IN THIS LESSON

  1. Night photography and its roots
  2. Astrophotography
  3. Star trails
  4. In practice: a first night out

Night photography and its roots

Night photography means working outdoors between dusk and dawn, when natural light is weak or absent. It has been recognised as a genre for more than a century. The low light calls for long exposures, from seconds to far longer, higher sensitivity, or added light. Its history began with the sky. Louis Daguerre tried to photograph the Moon on 2 January 1839, but the picture came out blurred. John William Draper made the first clear lunar photograph on 23 March 1840 from a New York rooftop, with an exposure of about 20 minutes. In 1932 Brassaï's book Paris de nuit, made with a tripod and slow film, made night work a serious art.

Astrophotography

Astrophotography is the imaging of the Moon, planets, stars and deep-sky objects. It relies on long exposures, because film and sensors gather light over time and can record objects too faint for the eye. Two problems follow. Light pollution from towns swamps faint stars, which is why serious imaging moves to remote sites. And the Earth turns, so stars drift across the frame; astronomers use tracking mounts that turn the opposite way. The Bortle scale, published by John E. Bortle in Sky and Telescope in February 2001, rates sky darkness in nine classes, from 1, the darkest skies on Earth, to 9, inner-city skies.

Star trails

If you let the stars move instead of fighting it, you get star trails: streaks that trace the sky's apparent rotation. A longer exposure gives a longer arc. The source gives typical exposures from 15 minutes to several hours, using the camera's Bulb setting and a cable release or intervalometer, with focus set to infinity and apertures such as f/4 or f/5.6. Long single exposures drain batteries and add sensor noise, so many photographers now take a series of shorter frames and blend them into one trail. Point the camera at the celestial pole and the trails become circles around it.

In practice: a first night out

This section is working practice. Use a sturdy tripod, turn off image stabilisation on the tripod, and use a timer or remote so your touch does not shake the camera. Focus manually: magnify a bright star on the screen and turn the ring until it is a tiny point, then tape the ring. Shoot RAW. Start wide and fast, for example f/2.8 and a few thousand ISO, and adjust the shutter time until stars stay points or become the trails you want. Give your eyes twenty minutes to adapt, use a red torch, and dress warmer than you think.

Try it today

  1. 01Look up the Bortle class of a site within an hour's drive and pick the darkest you can reach.
  2. 02Choose a night near the new moon with a clear forecast.
  3. 03Set up a tripod, focus manually on a bright star, and tape the focus ring.
  4. 04Make one frame where stars stay points and one series for a short trail.
  5. 05Include a foreground, a tree or a rock, lit only by the sky.