Consumer Reports: How well does your sunscreen perform?

With its ability to help protect us from skin cancer as well as wrinkles and brown spots, sunscreen is essential.

But a new survey finds that only fifty percent of us use it.

In advance of summer, Consumer Reports tested dozens of sunscreens and found some real surprises.

There are a lot of options when buying sunscreen. A survey from Consumer Reports found that even people who regularly use sunscreen don't always have a good understanding of what they're buying.

"People look at the SPF, or sun protection factor, and that's very important, but it's only one part of protecting your skin from the sun," said Trisha Calvo, Consumer Reports Health Editor

The SPF is a measure of how well a sunscreen shields your skin from UVB rays, which penetrate the top layer of skin and are the chief cause of sunburns. UVA rays penetrate deeper into the skin and can contribute to wrinkles. Both UVA and UVB rays can increase the risk of skin cancer.

"Consumer Reports recommends using a broad-spectrum sunscreen so you're protected against both kinds of rays," said Calvo.

Consumer Reports tested over 60 sunscreens to see whether they deliver the protection they claim.

In the UVB tests, technicians apply sunscreen to panelists' backs and have them soak in a tub for 40 or 80 minutes, depending on the product's water-resistance claim. Then the area is exposed to UVB light.

The next day, the test area is examined for redness. More than 40 percent didn't have the SPF they promised.

To check UVA, technicians pass UVA light through sunscreen samples. Again, some had problems.

But Consumer Reports found some sunscreens aced the tests and are a good value.

Among the best - Pure Sun Defense SPF 50 for about $6 dollars, Equate Ultra Protection SPF 50 for about $8 dollars, and No-Ad Sport SPF 50 for $10 dollars.

Consumer Reports also tested spray sunscreens.

Some of the best are Trader Joe's Spray SPF 50 for $6 dollars, and Equate Sport Continuous Spray SPF 30 from Walmart and DG Body Sport SPF 30 from Dollar General, both for $5 dollars.

But before you use spray sunscreens - especially on kids - you might want to talk to your pediatrician or doctor.