Technology
“to capture moving images the ccD transfers each frame to an extra sensor behind the main imager”
How camcorders work
Learn how the latest digital video cameras capture and record hi-def footage
Modern digital recorders fundamentally work in the same way as the original analogue camcorders of the Eighties – those bulky, VCR-recording devices wielded on the shoulder. They both comprise a lens, imager and storage medium, but the main differences are that today’s camcorders convert analogue data to a digital form and that the technology as a whole has miniaturised to a far more practical, handheld level. A camcorder uses a lens to focus patterns of light from a scene onto an imager – a CMOS sensor or charge-coupled device (CCD). The latter is a small semiconductor that houses around half a million photosites – tiny diodes sensitive to light that measure the number of photons that strike it before converting them into an electrical charge. The strength of this charge tells the camcorder during playback how intense the light at that point should be. Colour is recorded by measuring the levels of green, red and blue, because any colour can be replicated with a mix of these three primary shades. Of course, CCDs in camcorders have to record moving images, so the device must capture multiple frames. To do this, the CCD transfers each frame of video to an extra sensor behind the main imager in a small relay system. This second sensor transmits the electric charges at each of the photosites to the analogue-to-digital converter, while the first layer wipes itself blank, ready to capture the next image. The latest top-of-the-range camcorders pack an unbelievable amount of technology into a tiny body, relative to the video recorders we started with 30 years ago. The Hitachi Super Hi-Vision, for example, can shoot 33 megapixels (7,580 x 4,320 resolution) at 120 frames per second. That’s 4 billion pixels caught each moment – the same kind of detail seen on an IMAX cinema screen.
Video recorder tech We take a peek at the technology enabling us to shoot ever-better home movies
Laser reader
Curved body
Some older models of camcorders include a laser reader/writer for recording to and reading from miniDVDs.
Camcorders can be made shockproof (ie protected from falls) by padding the corners and building a solid frame with a curved shape that’s inherently strong.
Spindle A small motor can drive the miniDVD on a spindle at around 500 spins a second.
Lens The lens screws on to the top of the imager and focuses the light on the sensor underneath.
Materials Typically made out of light but durable plastic, some specialised camcorders (like the GoPro HERO3) are also sealed in order to make them waterproof.
028 | How It Works
www.howitworksDAiLY.com
