One of the most common questions I field about e-book readers, especially at this time of year, is “Don’t their screens wash out in sunlight?” On the contrary, manufacturers of these devices, including Sony and Amazon, say their digital devices are easier to read in sunny conditions than paper books.

To see if their claims hold up, I put the Amazon Kindle 2 and two Sony Readers (both recently discontinued) through informal tests in recent weeks.

I took the three devices and three books out to the patio of our cafeteria around noon on several sunny days. The books, all novels with few or no images in them, had type comparable in size to what I’d selected for the e-book readers. I chose the books to provide variety in the color of the print (which ranged from jet black to middle grey) and the hue of the paper (varying from bright white to near-brown).

I asked 10 or so staffers to rank the ease of reading them in the sun. Then I asked them what made one easier to read than others.

The e-book readers were unanimously judged easier to read in the sun than any of the books, for reason of lower glare. My lunchtime panelists typically found little difference in glare among the three e-book readers. Some did, however, say they found the type on the Kindle easier to read—an observation that tracks with my observation that the type on the Amazon devices is a little clearer that that of the Sony Readers. With the books, the whiter the paper, the greater the glare problem.

What explains these findings, when so many of us squint to read the screens of our laptops and cell phones in the sun? The screens of the Amazon and Sony e-book readers use a technology known as e-ink that’s quite different from the LCD and LED technology employed on the screens of computers and phones.

E-ink actually relies on the reflection of ambient light back to you to illuminate its screen. It appears e-ink reflects about the same amount of light back in very bright conditions as in normal lighting—making for fairly squint-free summer reading. An added bonus: That natural light source helps make e-book readers very energy-frugal, enabling them to run for days on a charge.

Obviously, this informal trial should not be confused with the highly scientific tests carried out when we formally rate products here at Consumer Reports. But it does support what e-book manufacturers are saying about their products. —Paul Reynolds