Projecting the image of the Sun from a telescope is another straightforward and inexpensive method to observe the Sun in white light. The projection method dates back nearly to the invention of the telescope itself. In its simplest form, the technique simply involves holding a thick piece of paper or cardboard a foot or two behind the eyepiece of the telescope when the scope is aimed at the Sun and brought to focus. The image from the eyepiece projects onto the paper screen. The greater the distance from the eyepiece to the screen, the larger the image. That's all there is to it.

To get a projected view on the screen with good contrast, place a small diaphragm made of cardboard over the top or bottom of the telescope tube to block unwanted sunlight from falling onto the screen. No other special equipment is required for this method, though some vendors sell a white screen and a mechanical holder that fixes on the back of the telescope or focuser to hold the screen in place.

You can also use a pair of binoculars mounted on a tripod-- with a cap placed over one of the two objective lenses-- to project the image of the Sun onto a screen. However, with binoculars, it's best to observe the Sun for only a few minutes at a time because the Sun's heat can damage the adhesive used to hold in place the glass prisms inside the sealed optical tube of the binoculars. With magnification of 7x to 10x, binoculars show much more on the Sun's disk than the unaided eye, but they are still limited compared to a telescope in terms of how much they can enlarge solar features such as sunspots, plages, and faculae.

SAFETY NOTE: When using the projection technique with telescopes or binoculars, remember the full intensity of the Sun is coming out of the eyepiece. So make sure no one, especially a small child, walks up and looks through it. For the same reason, it's also good practice to cover the finder scope of a telescope during a solar observing session.

The simple projection method works well for obtaining low-magnification and full-disk views of the Sun, larger sunspot groups, light-colored faculae, and for watching sunspots move across the face of the Sun each day during the Sun's 26-day rotation period. The method is also well suited for showing the Sun's disk to larger groups of observers, especially during partial solar eclipses.

Because the telescope is unfiltered when using the projection method and the Sun's full intensity falls into the optics, this method is best suited for small refractors or Newtonian reflectors of less than 3" to 4" aperture. Larger telescopes collect too much light and heat which may result in damage to the eyepiece. The projection method should be avoided with Schmidt-Cassegrain and Maksutov-Cassegrain telescopes. These instruments, which almost always have apertures larger than 4", will suffer heat build-up inside their sealed tubes leading to degraded views and perhaps permanent damage of the instrument.

The projection method also points the way to the simplest technique of all to observe the Sun: a pinhole camera. Just poke a tiny hole in a piece of cardboard or a thick piece of paper, aim the card at the Sun, and project the image onto a second piece of paper at least a foot away. This approach yields a small and faint image of the Sun, but it can reveal larger sunspot groups and the progress of a partial solar eclipse. Sometimes, during a partial eclipse, you can see multiple images of the eclipsed Sun cast onto the ground by the pinhole gaps between leaves on a tree.