So, by analyzing many tiny images and then using software to cleverly manipulate and combine them into a single image, a light field camera can capture, in effect, an enormous depth of field. This means an image captured by a light field camera can be used to create other versions of the image with, in theory, any focal plane and depth of field. So you could use a light field image to create versions where the foreground, mid-ground, or background objects are in focus. Even more intriguingly, at least in theory, a light field camera could even produce an image where everything in the scene is in focus!
This ability of light field imaging technology to produce "refocusable" images means that the ultimate "point and shoot" camera could be built ... no focusing, no aperture adjustment, just, er, point and shoot.
But, there's a potential problem. As the Wikipedia entry explains "The drawback of such a system is the low resolution that the final images have. As one microlens samples the light directions at one spatial point an increase in the number of image pixels can only be done by increasing the number of microlenses by the same amount."
Thus, the depth of field is dependent on the number of microlenses and the resolution is dependent on the number of pixels per microlens. So, if you increase the number of microlenses for a given sensor, the resolution drops but the depth of field increases. In other words, the resolution and depth of field are inversely proportional for given sensor geometry.
It's worth noting that the Lytro camera is specified as capturing 11 "Megarays" ... a wholly meaningless value as there's no definition anywhere as to what a megaray might actually mean.
Enough theory, let's get to the Lytro camera. First of all, the design is sensational. A small rectangular box (1.6 in x 1.6 in x 4.4 in) with a single large lens (f/2) at one end (with a magnetic lens cap -- very slick) and a touch sensitive screen at the other.
The screen end of the box is a textured, rubber-like surface while the lens end of the is a smooth metallic surface. The overall weight and balance of the device is perfect.
On the textured part of the top surface is a depression that you press to take a photo, and sliding your finger left and right above the screen optically zooms in and out. On the bottom surface at the screen end is the power switch and a pop-off cover for the USB 2.0 connector. Physically, that's it; a very clean design and very elegant.
The touch sensitive screen can be swiped left to review and manage photos (you can zoom in and out and refocus on any point) and swiped up to reveal the menu system. When you are taking photos In the "Creative" mode you can tap on the screen to choose the focus point.