SILICON CHIP
Publisher & Editor-In-Chief
Leo Simpson, B.Bus.
Editor
Greg Swain, B.Sc.(Hons.)
Technical Staff
John Clarke, B.E.(Elec.)
Robert Flynn
Advertising Manager
Paul Buchtmann
Regular Contributors
Neville Williams, FIREE, VK2XV
Bryan Maher, M.E. B.Sc.
Jim Yalden, VK2YGY
Garry Cratt, VK2YBX
Jim Lawler, MTETIA
John Hill
David Whitby
Photography
Bob Donaldson
Editorial Advisory Panel
Philip Watson, VK2ZPW
Norman Marks
Steve Payor, B.Sc. , B.E.
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2
SILICON CHIP
PUBLISHER'S LE'l-l'ER
From the electronic shutter
to high-definition TV
This month we have reviewed a fancy 8mm video system from Sony
which includes a camcorder and a VCR with PCM stereo sound editing
facilities. In the brief time we had to familiarise ourselves with the
equipment we were very impressed with its performance and innovative features. But while both the camcorder and VCR abound with
new features , the aspect which most fascinated us was the electronic
shutter.
For anyone who has even a smattering of knowl,edge of the workings
of a TV camera, the concept of an electronic shutter which can
operate at 1/l00oth of a second or faster is truly incredible. Such a
concept is not feasible with conventional video camera picture tubes.
It has been made possible by the new solid state cameras which use
CCD (charge coupled device) imaging circuits. In these cameras, the
picture from the lens system is focussed directly onto the integrated
circuit which is scanned electronically to extract the video signal.
In just a few years, CCD cameras have surpassed conventional
cameras in their overall performance, picture quality, light sensitivity
and now with the addition of "electronic shutters". Many ENG (electronic news-gathering) cameras used by televison stations now have a
couple of shutter speeds, typically to 111000th of a second although the
Sony camcorder reviewed in this issue runs as high as 114000th of a
second. As we point out in the review, there is no shutter as such. The
CCD is merely allowed to build up charge on its picture elements for a
much briefer time than the normal 20 milliseconds. So for a 1/4000 sec
shutter speed, the CCD is " open" for only 250 microseconds.
The latest CCD imagers have the capability of a 64µs shutter speed
(1/15,625 sec). What this means is that cameras using these imagers
will have the potential for really high speed photography, much faster
than even exotic film cameras can achieve. Combine that with the
much higher picture resolution now possible and near-future
developments in high-definition television (HDTV) and you have to conclude that the death knell of movie film is not far off. In the future ,
when you go to the movies, you will see HDTV tapes, not film.
How long will it be before these developments take place? It will be
probably ten years or more before HDTV theatres become commonplace. In the meantime, have a look at the picture quality available
from the latest 8mm video camcorders when shown on a direct video
monitor. It is surprisingly good.
Leo Simpson
