Tuesday, August 14, 2012

Shooting for the Stars

An hour before sunset
August is a great month for photographing stars and other celestial objects, especially here in Oregon.

This post is an introduction to photographing the stars and celestial events.

Equipment List:

  • Camera
  • Tripod
  • Wide angle lens (less than 30mm)
  • Remote shutter release
  • Flash light 

The first thing you need to do is find a location away from the lights of the cities. Even a small town, 350 people or less, can generate enough light pollution to wash away any chance of seeing and capturing decent star fields.

Ideally, your location will be hundreds of miles from the nearest town, but unless you live in the middle of the Mojave Desert, say Death Valley, this isn't likely. So find a location that is as remote as possible, ocean beaches away from large populations area  good choice.

The Beauty of Death
The next thing you need to do is to arrive early, a least an hour before sunset.

This is a great opportunity to capture some golden hour images of interesting subjects. But more importantly this allows you investigate the area during daylight hours to find your location to shoot from.

Look for spots that don't have too many objects in the field of view. Ponds, fields, distant hills, farm equipment and trees in the distance are great subjects to add to the impact of and give scale to vast expanse of the sky.

Don't expect much star action to show up until an hour after sunset. Two hours is better. Bring a book to read. Photograph other things. Find something to do to blow the two hours you will wait.

277 seconds, ISO 100 - Not Long Enough
The secret to photographing the stars is to take a minimalist approach. Place the horizon as low as possible in the frame, but keep the horizon in the frame to anchor the image. The stars by themselves are pretty boring, little white dots on a black or blackish screen can be as boring as connect-the-dots and no pencil.

Much like the Ying-Yang, one can appreciate the light only because of the dark. One can appreciate the beauty only because of the ugly. The horizon as an anchor allows to appreciate the infinite expanse of the universe by grounding it to the finite world we live on. As a point of note; too much horizon, having the horizon too close to the center of the frame narrows the view of the sky, eliminating the impact.

33 seconds at ISO 3200 - Exposing the Sky
When exposing the sky, there are two different methods I use; High ISO/Fast Shutter and Low ISO/Slow Shutter. In either case I use a remote shutter release.

My typical camera settings are as follows:

  • Camera Mode: Manual
  • Shutter: Bulb Mode
  • Aperture f/3.5 or lower if possible
  • ISO: Depends
If I am trying to capture the star field, or even the Milky Way, it is  important to have the shutter be fast. By fast I mean at about 20 seconds. Anything longer than 20 seconds will lead to blurring of the stars. Remember, the world keeps turning so the stars position in the sky are always shifting as you will see in the images below. The image to the right was shot at 33 seconds. The image above-left was 277 seconds.

To capture all of the stars possible in twenty seconds means having to jack my ISO up high. For this type of shot, above-right, I typically use ISO 3200. You can see the number of stars captured is greatly improved over the image shot at 277 seconds using ISO 100.

18 Minutes at ISO 100.
1127 seconds sounds like a long time. It is a very long time when you are waiting for a photograph to be taken. 18 minutes can last an eternity. Einstein was right; time is relative.

Because the ISO was set so low, only the brightest of stars make an appearance in the star trails. Look again at the image exposed for 33 seconds, above, at ISO 3200. Look at the shear number of stars. The image to the left is the exact same scene, but because the ISO is only 100 the number of stars present are limited to only the brightest.

I could shoot a long exposure at ISO 320, but the light at the horizon, city lights from a small town 30 miles away, would have exposed the entire scene white. That is the issue with light pollution. The more remote you can get, the more you can play with higher ISO scenes.

http://www.astro-observer.com/dark/lpmapusa.html This is a link to a map of light pollution is the United States. Unless you can get to one of the black areas on the map, you will have to deal with light pollution.

30 Minutes at ISO 100
The longer you expose the more chance you have of capturing other objects in the sky, such as airplanes and occasionally even a satellite, if it is bright enough.

In the case of the image on the right, the stars are uniformly making the same pattern in the sky. There is one particularly bright anomaly. Welcome to the Perseid Meteor Showers.

Capturing events like the Perseid Meteor Shower is one part being prepared and one part being lucky.

If a meteor is flashing in front of camera during exposure, you are lucky. If it is bright enough to to be captured you are lucky, unless your ISO is higher than 100.

Be patient. Experiment. Have fun.

I would like to thank my friend Janeen for hosting this interstellar kegger. She was a wonderful host to our ragtag band of photographers.

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