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Digital Camcorder Advances Yield Great Still Photos, Compact Tapes

Digital Camcorder Advances Digital Camcorder Advances

Digital video today, like digital still photography, is marked by rapidly accelerating technology that leaves us breathless each time a new product is introduced. Each new camcorder seems to eclipse the capabilities of its predecessor. Two new developments that have expanded the horizon of video camcorders have been the advent of digital signal processing and the mini digital video tape cassette.

Camcorders are becoming more useful for still photographers by packing more sophisticated still, video and audio capabilities into smaller units that allow easy down-loading, editing and impressive multimedia opportunities. Sony's new DCR-PC110 Digital Handycam camcorder is the first to integrate both megapixel imaging and MPEG movie mode for still images or video clips.

What do these new features make possible? Digital signal processing changes everything from the design of the camcorder to the way tapes are edited to what special effects are possible. Like digital still cameras, the new video camcorders translate light values through the lens into 'on' or 'off' values at the pixel level. This binary system of recording images has many benefits, from reproduction without quality losses, to better color fidelity, enhanced resolution, easier editing, and now, a real and viable means of capturing stills.

The mini digital video tape cassette is one-ninth the size of a VHS tape and less than half the size of an 8mm or audio tape. This makes possible a palm-sized video camcorder that is eminently suited to handheld videography.

We have all seen at one time or another a very poor quality smeared still image 'lifted' from a conventional VHS video tape. This is all one could hope for before the application of digital technology. While these images served a purpose - a basic still thumbnail sketch - the lack of quality made them useless for all but reference applications. A video camcorder works much the same as a motion picture camera in that the moving image is in fact a series of stills (30 images per second for film, 60 images for video NTSC). The human eye and brain cannot separate these images and instead sees them as a seamless moving image. In the past, these images were limited to 480 X 640 resolution (like most TVs), and were the product of a camera usually weighing several pounds and requiring a major tripod for support.

The new generation of digital video camcorders allows image capture at resolutions up to XGA (768 X 1024), resulting in a much more useful still image, produced by a camcorder no larger in size than a small digital or conventional 35mm point-and-shoot. Also instrumental in producing higher quality stills is the development of progressive scanning with an RGB filter, which improves image quality by interlacing 480 horizontal scans (NTSC standard) of each frame. Interlacing means that as the image is scanned, every other horizontal line is recorded and then goes back to scan the in-between lines to give a flicker-free image. This development came about because on early televisions the image at the top of the screen faded slightly before the last lines were scanned at the bottom of the screen, causing flicker.

One last element that contributes to the success of the current DV camcorders is the general adoption of optical or mechanical image stabilization. Whereas a shutter speed of, say, 1/10 second will produce acceptable results in video (remember, those 60 frames per second are not seen as 60 individual frames) allowing handheld use in low light, this shutter speed would be marginal at best for a still camera without a tripod. Image stabilization is roughly the equivalent of using a monopod; that is, if you can get sharp handheld shots at 1/30 second, you can probably go down to 1/8 second with a monopod or image stabilization. Two stops may not sound like much, but it is often the difference between using available light or having to add flash or a video light.

The grand total of these improved technologies is that one can now achieve a decent quality still image (a slightly-less-than 1MB file) from a handheld video camcorder. Is that a suitable substitute for a professional quality still camera? Well, no. But for use on a web site, for email communication, or for small reference stills, the answer is yes. Also, for the amateur videographer who replays through a television, the answer is yes.

Producing quality stills from a video camcorder has not until recently been a priority for camcorder manufacturers. It was not until they learned there was a viable market for this feature, and the technology became capable of producing such an image, that they turned their attention to producing stills. Sony, Canon, Panasonic, JVC and Sharp all produce quality digital video camcorders with still frame capability. Some, such as the Sony DCR-TRV20, have a megapixel chip that permits recording XGA resolution. Others retain VGA resolution, but produce much higher quality than earlier chips of the same resolution. Sony incorporates their MemoryStick technology for recording stills; others, such as the Canon Optura PI, record onto DV tape.

Most camcorders are able to record 500 to 700 images on a tape cassette. Each image occupies approximately six seconds of tape time, allowing the user to add audio to the still. For documentary work, this would be handy. Other features enhance the camcorder's versatility. One such control is Canon's Digital Motor Drive, employed in the Optura and Elura models. Digital Motor Drive allows the user to record 30 individual still frames per second. Now that's a high speed motor drive! Connectivity varies with the manufacturer, but most employ an RS232 port or Firewire specifically for downloading stills.

At the premium end of model lineups are the Canon GL1, Canon XL1 and Sony DCR-TRV900. These camcorders perform all the aforementioned functions, but do so with 3-chip technology: one chip for each primary color. These camcorders rival broadcast cameras for image quality, though they are larger and more expensive than their lesser siblings. An interesting development in the Canon models is the use of non-interlaced scanning of the CCD. This technique is what caused flickering on older televisions, but new developments make it possible today, adding increased clarity and fidelity to the still image as well as a 'cinematic' look to motion video.

This new generation of camcorders empowers photographers with the opportunity to record stills as well as video and audio with a tiny and lightweight unit (though with lesser resolution) than still camera options.

These camcorders also now allow photographers to more conveniently show their still images in a multimedia presentation, expanding the opportunities for communicating their visual experiences. The recent, much-publicized Ken Burns PBS documentary, "Jazz", well-illustrates the power of this medium.

All in all, the new lineup of digital video camcorders is very impressive. There are more than 20 digital camcorders with dedicated still photo functions available. They do not replace their still counterparts in the digital world, but who knows, in a few years they may. Until then, the videographer is most likely to enjoy these capabilities, and savvy amateurs and web photographers, perhaps even motion study researchers, can put their newfound digital still photography capabilities to work.

Ed Coleman
Story Author: Ed Coleman
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