How a Light Field
Camera Can Focus
Anything
(^134) PART 2 HOW DIGITAL CAMERAS CAPTURE IMAGES
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We’ve all wished there were a magic control on our cameras that would
let us refocus a picture after it’s been taken. But we were told, not in the
camera, not in the darkroom, not in our computers, was there any magic
that would let us turn a badly focused picture into a sharp image. But a
Stanford grad student named Ren Ng has found one place you can refo-
cus a photograph—the fourth dimension. Ng has built a camera that
records not simply one thin slice of light, but all the light rays that pass
through the lens, and where their focal points will land—before, behind,
or smack on the image sensor.
In an ordinary camera, the light rays coming from each point
making up the subject the camera is focused on are bent so
that they converge at the camera’s focal plane, where film or
a light-sensing microchip waits to record those points of light.
Light rays originating outside that focus area miss the mark,
converging behind or before the focal plane, creating blurry
circles of confusion (see Chapter 3).
In the light field cameradeveloped by
Ng, the light rays pass through another set
of lenses between the camera’s main lens
and the image sensor—90,000 lenses, in
fact. The lenses are microlenses arranged in
a lenticular lens array that covers the surface
of the sensor.
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