There is this commercial that has been coming on lately showing some people reading the Kindle at the beach. Why is this a selling point? It has to do with the way the Kindle works compared to something like the iPad. I would take a picture, but I have neither of these devices. Instead, I will make a diagram.
Maybe you can’t tell from my diagram, but I am using the black rays to represent light reflected from the Kindle and red rays to represent light produced from the iPad. And that is the key. The Kindle does not have a light source, it is very similar to a piece of paper. The iPad is kind of like a flashlight in that it is a light source.
So now, you are in the bright sunlight. For the kindle, the brighter the external light source, the more light is reflected. This is good. Your eyes adjust to bright light to not let as much light in. The result is that you can see the Kindle just fine in the sunlight. The iPad only produces a finite amount of light. The brighter it is outside, the less you can see it. First, your eyes are adjusting to just looking at brighter things (so that doesn’t help). Also, there is more light reflecting off the surface of the iPad making it harder to see the image below the glass (this is just like looking through dark windows.)
In the opposite case – in a dark room, clearly the Kindle is at a disadvantage. You need some external light to view it and read in bed. This is actually better for your eyes (so I am told), but it might disturb anyone else in your bed that wants to go to sleep.
In the end, I have neither of these devices. I still read dead-tree books. Oh, and I doubt I would ever take even a book to the beach. It’s not that I don’t want to relax, I would just rather play or dig a big hole.