How The Camera Deals With The Image

When the image makes it through the lens it gets recorded in various ways by a small chip located near the lens, called the charge-coupled device (CCD). There are two sorts, determined by which kind of camera you have:

• Single-chip. These dominate the lower, domestic end of the market. It collects over 300 000 pixel bits of information, which sounds a lot but is considerably less than the three-chip.

• Three-chip. This one is found in any of the better camcorders in the mid and upper ranges. The big difference here is that there are three chips, each gathering 300 000 bits of information, but this time each chip gathers just one colour each: red, green or blue. The single-chip gathers all colours together and so has to squeeze all three groups of information into one chip. The additional quality of the three-chip is worth about an extra 20 per cent in terms of picture and colour resolution.

If you want to make programmes for broadcast then you need to get a three-chip. Most people will not notice the difference between single-chip and three-chip, but broadcasters will notice and do not
accept certain quality of pictures. But if you intend to show only on the web, this difference is going
to be reduced later, so it may not be useful.

At this stage the camera sorts out how much information can be stored and how much has to be
left behind. Mini-DV tapes do not have the capacity to store all the information that a camera
could record but are significantly better than VHS. In terms of a ratio of information kept to that
thrown away, mini-DV is 5:1, compared to 7:1 for analog Hi8 and 15:1 for VHS. How well a camera
squashes down its information is crucial. The new generation of HD cameras have suffered from a
poor compression method. It remains a problem for manufacturers to convince the market about HD
because the recorded picture is so reduced from what it should be, given the huge size of each frame of HD video.

When The Image Gets Recorded onto Tape

Digital tape is much more rugged than that used for analog S-VHS or VHS video. It is made of an
advanced form of Metal Evaporated (ME) tape. It consists of a double-coated magnetic layer, which is in turn coated in tough carbon. This enables stored digital information to be played back with minimal loss of quality and less picture noise, or interference. ‘Bleeding’ from the audio track to the video tracks is also unlikely, further reducing interference.

Solid-state cameras record onto discs but have to use a sophisticated form of compression to enable it to do so. In consumer models images are recorded onto a fixed hard drive or onto DVDs, though the latter have failed to take off in the consumer sector in the way manufacturers would have liked.
Cameras using hard drive recording have become more widely used, possibly a result of the iPod effect, where consumers understand and trust mini hard drives. A further development has been in removable hard drives. For filmmakers using cameras such as the Canon XZ2 or Sony PD170, the favourites of many low-budgeteers, hard drive recording was not possible until large removable 80GB drives such as Holdan’s Firestore made it to industry shows.

The term ‘broadcast quality’ has changed considerably since DV became a consumer  item; in terms of the consumer it has become a loose term and often simply  refers to a quality far above that offered by analog, but not necessarily meeting  broadcast technical quality guidelines. Whatever the publicity blurb says, check  with an independent advisor first before committing yourself to an expensive camera  that claims to be broadcast standard but stops your programmes being accepted  by television companies.

Bookmark It

Hide Sites