The Great American Solar Eclipse is less than three weeks from now, and millions of people are expected to head to the “band of totality” to see it in all its glory. In addition, this solar eclipse is set to be the most photographed in history when it happens Aug. 21, with many bringing their cameras with them.

And in the age of smartphones, it won’t just be professional photographers who will be taking shots. However, the pros recommend that people not point their camera directly at the sun, even during a near-full eclipse, without a solar filter attached to the lens. The only exception would be that brief period when the sun is totally blocked by the moon.

“IT IS NEVER SAFE TO LOOK AT THE SUN WITHOUT PROPER EYE PROTECTION WHEN ANY PART OF IT IS VISIBLE BEHIND THE MOON!” camera-maker Canon states on its eclipse photography website. “THIS ALSO INCLUDES NOT LOOKING THROUGH YOUR CAMERA’S VIEWFINDER WHEN PHOTOGRAPHING THE ECLIPSE – USE A SOLAR FILTER ON THE FRONT OF THE LENS, AND LOOK THROUGH YOUR LCD SCREEN INSTEAD OF THE VIEWFINDER!”

“The #1 rule for observing a solar eclipse, or for looking directly at the Sun at any other time, is safety first,” the American Astronomical Society says on its website. “As noted elsewhere on this site, with one exception, it is never safe to look directly at the Sun without a special-purpose safe solar filter. That exception is during totality, when the Moon completely blocks the dazzlingly bright face of the Sun. On August 21, 2017, this will happen only within the roughly 70-mile-wide path of the Moon’s dark inner shadow from Oregon to South Carolina — and only for a minute or two.”