By Birger Andresen,
Trondheim Astronomiske Forening
 |
The method of projection is safe and gives an excellent image of the Sun which several persons can view at the same time. Click on the image for full resolution. Adobe Illustrator
EPS (CMYK)
Illustration: Trond Erik Hillestad
|
MULTIPLE EXPOSURES ON THE SAME IMAGE
Many cameras give you the possibility of taking multiple exposures without rewinding the film. In that case you can show a whole eclipse from beginning to end on the same image. This can be a suitable challenge for more experienced solar photographers. The camera should then be placed on a tripod which is not moved as long as the eclipse occurs. Take for example a photo every 5 or 10 minutes, which will give a nice distance between the solar disks. Use a constant interval between the exposures to get a balanced composition and choose a time to start that gives you a photo when the eclipse is at its maximum. A 35 mm camera with 50 mm lens covers an area of the sky of 49 degrees, measured along the diagonal of the negative. The Sun will pass through this field in around 3,5 hours. A 50 mm lens is therefore sufficient to capture a full eclipse, which typically happens during a 2,5 hour interval if it’s total or annular where you are, less if it’s partial.
You must set the camera so you will capture the whole movement of the Sun during the eclipse on the image field. To do this you need to know the path of the Sun. You also need to know the time for the eclipse’s beginning and end, as well as its maximal phase, relatively exact from your location of observation. Make sure you won’t move the camera field when you rewind the camera for a new exposure or bump into the tripod.
PROJECTIONS OF THE SUN ON THE GROUND THROUGH LEAF-COVERED TREES
If the light from a partial obscured Sun passes through a small hole, an image of the solar disk is created on the ground. The leaf-cover in a tree will often provide lots of such small holes and equally many projections of the solar eclipse in the shadow of the tree. The more of the Sun is covered by the Moon, the sharper are the projections under the tree. It’s well worth a picture or two. Here you’ll use the camera in a regular manner, just remember to turn off the flash.
You can also make a cardboard full of small holes which you hold in a suitable distance from the ground or for example in front of the face of a friend. The size of the projections can be adjusted by changing the distance from the cardboard to where you project the obscured solar disks. A little fantasy can give you great photos.
 |
Below a leaf-covered tree hundreds or thousands of partially obscured suns are created during a solar eclipse. This photo was taken on August 11,1999 in Austria when around 70% of the Sun was covered by the Moon.
Photo: Oddleiv Skilbrei
|
