Solar Projection
Small telescopes are especially suited to the solar-projection method. Seen here is a simple projection system made from a cardboard box with a piece of white paper as a projection surface. A surprising amount of detail can be seen with this setup.
Sky & Telescope photo by Craig Michael Utter.
One method of solar observing that requires no filtration whatsoever is solar projection. An eyepiece is placed in the telescope's focuser and used to project an image of the Sun onto a convenient flat surface. Telescopes with folded light paths, such as Newtonians or Schmidt-Cassegrains, are not recommended since the converging beam of light can produce enough heat to damage internal components. A small refractor is best — a long skinny tube with a lens at one end and a focuser and an eyepiece at the other. Start by attaching a cardboard shield around the tube near the front lens, then cover (or remove althogether) the small finderscope that's attached to the larger tube. Binoculars can also be used; mount them firmly on a camera tripod, place a cap over one side’s front lens, and put a cardboard shield around the other one’s tube.
To aim the instrument safely, point the tube toward the Sun and move it around until sunlight begins to pour out of the eyepiece.
Sky & Telescope illustration
Don’t look into the eyepiece! Place the white card behind the eyepiece (in the shadow cast by the cardboard shield) and focus the image. Experiment with the card’s distance from the eyepiece to get the most pleasing combination of size and brightness of the Sun’s projected image.
This projection method has one advantage over all the others: many people can observe the solar surface at the same time. But if you’re viewing the Sun with a group, never leave a telescope or binoculars unattended — especially when children are about.
For more information about this method of Sun watching, see "Observing The Sun By Projection."
