…continuedViewing the Sun Safely
"Observing the Sun By Projection"). For a quick first look by this technique, hold a white card or paper a foot or two behind the eyepiece of a telescope or a pair of binoculars on a tripod. The card must be shaded from direct sunlight. Focus until the Sun’s limb appears sharpest. Almost as much detail will be visible in the projected image as when the Sun is viewed directly through an aperture filter.
When viewing the Sun via the projection method, follow these precautions for safe viewing:
To do any of this, you’ll need a projection screen attached to the telescope to hold the paper. Such screens are sometimes supplied with small refractors. You can make your own (or better yet a projection box, to improve contrast by keeping daylight off the paper) by experimenting with cardboard, wooden dowels, bolts, and plywood. Plan the distance from eyepiece to screen to be 107d/(m – 1), where m is the telescope’s magnification and d is the diameter you want the Sun’s image to be.
When examining the image, try flicking the paper rapidly back and forth. low-contrast detail that was lost in the paper’s surface irregularities will pop into view.