Kamis, 27 Desember 2007

How to Photograph an Eclipse of the Sun

Introduction

The few minutes of time that the sun is totally eclipsed by the moon are precious. If this is your first eclipse experience, plan on enjoying the first half of the event visually before trying to photograph it. You can always trade photographs with your new friends from the eclipse chase later.

Shooting a Total Eclipse

Things You'll Need

Steps

1 Step One

Set up your equipment early. You'll need a tripod and cable release to minimize vibration for short exposures; a steady platform for longer exposures.

2 Step Two

Load your camera with fast (ASA 400) slide film.

3 Step Three

Use a long focal length lens ranging from 200 to 2,000 mm. Longer focal lengths won't show the complete disk of the moon on the film, but will show details of the prominences better.

4 Step Four

Shoot a range of exposures.

5 Step Five

Use the 200mm lens for exposures of several seconds to get the outer coronal features.

6 Step Six

Shoot a range of 1/500 second to 2 seconds if you're using a guided telescope.

7 Step Seven

Save an exposure or two for the diamond ring. Use a setting of about 1/125 second to capture both the emerging sun and some of the corona.

8 Step Eight

Remember to enjoy the total eclipse. If your camera doesn't function during the eclipse, sit back and enjoy the view, then get upset.

Tips & Warnings

  • You can shoot pictures of an eclipse on a ship. You must use shorter exposures, as the ship is moving.

Shooting a Partial or Annular Eclipse

Steps

1 Step One

Use a regular camera and take pictures of the projected image of the eclipsed sun.

2 Step Two

Shoot the projected image and some of the people who are viewing the eclipse with you. Have one of them hold the projected image sheet and take a normal group picture.

3 Step Three

Use a solar filter and a camera that can be attached to longer focal length lenses or a telescope to take pictures directly of the moon eclipsing the sun.

4 Step Four

Make sure the solar filter is suitable for the purpose of viewing and photography of the sun. If the filter isn't strong enough, you could ruin your camera and your eyes.

5 Step Five

Load your camera with 400 speed slide film.

6 Step Six

Attach a lens with a focal length of 200 to 2,000 mm. The size of the image of the sun will be the focal length of your lens divided by 100. A 200mm lens will result in an image that's 2mm in size on the film (slide or negative). A 2,000mm lens will produce an image that's 20mm in size.

7 Step Seven

Mount the solar filter at the front of all optics. It should not mount on the eyepiece.

8 Step Eight

Set up a tripod to hold the camera steady with the longer lens. A cable release is also recommended for longer focal lengths.

9 Step Nine

Use the light meter in the camera to gauge the exposure for your film.

Tips & Warnings

  • Two common material types are used in making solar filters for telescopes and cameras. Mylar filters will create a blue image. Glass filters will generally produce an orange or yellow image. In our experience, glass filters are better for photography; Mylar, better for viewing.
  • We use 400 speed film (slides) at an exposure of 1/250 second with a 90mm f/18 telescope and camera combination. As the eclipse passes the 50 percent point, we start using 1/125 second.

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