Photographing the total solar eclipse with a smartphone

— -- Millions of people are expected to flock to cities across the United States on Aug. 21 to witness the total solar eclipse.

Most of the picture-perfect images you'll see from this celestial phenomenon will be taken with professional-quality digital cameras on tripods or shot through a telescope. These images typically are not single photographs but composites of multiple photos using various exposures that are digitally combined for a stunning result.

"Most of them are composites, which I will be producing," said San Francisco–based photojournalist Peter DaSilva, who will be traveling to Madras, Oregon, to photograph the eclipse on Aug. 21 for ABC News.

"In capturing multiple exposures during totality, you can create a composite image with a wide tonal range, producing one of these beautiful images," he told ABC News in a recent phone interview.

Most people, however, will likely be using their smartphones or digital cameras to capture the awe-inspiring event. Many of these images will be blurry and overexposed or underexposed, DaSilva said.

But you don't have to be a professional photographer with expensive equipment to make your photos more spectacular. All you need is a little effort and preparation.

Safety first

You never want to look directly at the sun with your naked eyes, except during the brief totality phase of the eclipse, when the moon entirely covers the sun's beaming face. Unprotected direct exposure to the sun can cause permanent damage to your eyes, and the same is true for your camera lens, according to NASA.

In addition to having ISO-certified eclipse glasses to protect your eyes, be sure to have an extra pair to cover your smartphone or digital camera lens. Or buy a solar photography filter for the moments before and after the phase of totality, when the sun is still blinding. Do not use regular sunglasses.

When totality begins, remove the glasses or the filter from the lens and shoot normally with the camera. Remember, you'll have only 2 1/2 minutes or less to take photos.

As a precaution, you should keep special solar filters, eclipse glasses or handheld solar viewers over your eyes at all times when looking at the solar eclipse.

"Using optical filters to photograph the eclipse when you are not on the path of totality is inherently risky because you are looking at the blindingly bright solar surface," NASA says in its guide to photographing the Aug. 21 eclipse. "NASA makes no recommendations about how to safely photograph the partial eclipse phases because of the huge number of optical filter and camera models that may potentially be used and often with unsafe outcomes."

Practice makes perfect

NASA recommends that smartphone users practice photographing the full moon before the eclipse to learn how to manually adjust focus and to get an idea of how large the eclipsed sun will appear with your camera lens.

With most smartphones, you can adjust the focus and exposure with your fingertips. Tap the screen and hold your finger on the image of the moon to lock the focus. Then, keeping your finger pressed on the screen, swipe up or down to adjust brightness. Don't count on your phone's autofocus to do this.

There are several smartphone apps for iPhone and Android that claim to enhance your device's photo abilities, and you should consider testing as many of them as you can before the eclipse.

"The more test shots you can take in the days and weeks before the eclipse, the less time you will waste when the eclipse occurs," NASA advises in its photography guide.

DaSilva, who will be shooting the Aug. 21 eclipse with several cameras, said he has been researching and practicing techniques for months and has created a cheat sheet on the different exposures needed to capture totality.

He suggests buying good-quality eclipse glasses as well as a strap so they can hang around your neck when you take them off and be within reach when you need to put them back on.

"Unless you practice and have everything lined up, you're going to get frustrated and be wrestling with your camera rather than enjoying the eclipse," he said. "You have to be prepared, and you have to be deliberate at what you do, and then the rest is up to you to actually pull it off."

Invest in a tripod and a telephoto lens

NASA says a telephoto lens system, which acts like a magnifying glass, is "absolutely a must-have" for photographing an eclipse with a smartphone. Most telephoto lenses clip directly on to the smartphone over the existing lens and provide total magnification of 8x for less than $20 and 12x for less than $40, according to NASA.

Remember, telephoto lenses magnify the intensity of light hitting the camera's sensor, so make sure it's protected with a solar filter when shooting before and after totality.

DaSilva recommends purchasing a tripod for your smartphone or digital camera to prevent shaking, as well as a sandbag to keep the tripod sturdy in case there's wind.

Some 12x telephoto lens systems include a tripod and a mounting bracket for the smartphone.

Tripod adapters for smartphones can be found online and usually cost $3 to $10 brand new, according to NASA.

Be realistic

Smartphones were never meant to take images of the sun and moon, so don't expect incredible photos of the eclipse.

"Your most difficult challenge will be in managing your expectations! Smartphones were never designed to do sun and moon photography," NASA cautions in its photography guide. "The standard lenses are very small and provide hardly any resolution at all for even the largest objects in the sky like the sun and moon."

DaSilva said Aug. 21 will be his first time witnessing a total eclipse. And while he and other professional photographers will be solely focused on taking photos, he urged the public to focus more on enjoying the once-in-a-lifetime experience.

"Our eyes are so much better than any camera," he said.