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MITSUBISHI CCD-400E COLOUR VIDEO CAMERA
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WHAT OUR EXPERTS SAY...
Choosing the most appropriate lens for a
video surveillance camera has developed into something of a black art. Whilst
there are all kinds of helpful formulae, charts and tables, a lot of the time
it comes down to the installer’s experience and the price the end-user is
prepared to pay. The Mitsubishi CCD-400 colour video camera effectively
overcomes most of the complications concerned with lens selection, opens up a
range of alternative possibilities and solves a several other commonly
encountered problems, into the bargain.
The camera uses an 0.25-inch CCD image sensor
with a total of 440k pixels (effective), the stated low light sensitivity is
down to 1 lux (maximum gain) and resolution is quoted at 430 lines, using an S-Video
connection. To be honest it’s not much
to look at, an anonymous little black box just about sums it up. It measures 66
x 55 x 104 mm and apart from the colour, it looks like a dozen other compact
surveillance camera bodies, except that this one isn’t just a body, it’s the
whole camera, lens and all. Where you would normally expect to find a lens
mounting collar is the front optical element of a miniature motorised zoom lens
assembly, with autofocus and mechanical iris facilities built in. This sort of
all in one design is not exactly a new idea, in fact the CCD-400 is a
development of the similarly configured Mitsubishi CCD-200, Bench Tested right
here in 1995. Then, as now, it is built around a self-contained inner-focus zoom
lens assembly, similar to the types used on domestic camcorders. The new camera
has an increased zoom range, up from 8X to 14X; it also has a wider range of manual
and automatic exposure functions, and external control facilities, designed to
allow it to be used with a PC or proprietary telemetry and control systems.
We’ll come to that in a moment, but first a closer look how the camera has been
put together.
The large lens dominates the front of the
camera, the lens surround is fitted with a 46 mm threaded collar, designed to take
a screw-on filter. This will both protect the lens, and could come in useful in
tricky lighting conditions. The sides and top of the case are mostly bare; a
mounting plate with a standard threaded boss is fitted to the underside of the
case, it’s held in place by four small screws and can be moved to the top of
the case, if required. In contrast the back panel of the camera is very busy
indeed. There’s a fair few sockets; two BNC connectors handle composite video
out and external sync in. It has two mini DIN sockets; a 6-pin type handles
S-Video (Y/C) output, and below that there’s a 9-pin socket which is used to
carry RS-232 data. Lastly there’s a 3.5 mm power input socket for the 12 volt
DC supply; a suitable plug-in mains
adaptor is available from Mitsubishi as an option. There are only four
controls: three buttons and a miniature slide switch, that between them,
control a commendably wide range of functions
The steel case is in two halves, inside
there’s what amounts to an exoskeleton chassis, with printed circuit boards
mounted on the inside of the frame, surrounding the barrel-like lens mechanism.
Access to the lens is very restricted, hopefully it shouldn’t become necessary.
The case is reasonably well protected against the ingress of dust or moisture,
though it is only rated for indoor use, in a normal operating environment.
All of the camera’s lens and exposure
functions are controlled from a set of menu-driven on-screen displays, using
the three buttons on the rear of the case. The buttons also act as manual
controls for setting the zoom, iris and white balance, without having to delve
into the menu.
The on-screen display is a good place to
begin a tour of the various functions. The first page of options begins with
the lens, this leads to a second sub-menu covering zoom and focus functions.
There are four zoom speed settings and a choice of auto or manual focus. The
brightness menu calls up sub-menus for setting manual or auto iris and video
gain. The third option is for adjusting backlight compensation. Menu option
four is for setting the electronic shutter, there are 8 speeds, between 1/50th
and 1/10,000 th. second. Next is the detail or sharpness control, presettable
in 15 steps. The colour menu has settings for white balance lock, (auto,
indoor, fluorescent, sunlight and fixed) plus adjustments for R-Y and B-Y gain
and hue.
The second page of menu options includes a
simple character generator, used to create a camera ident (up to 8 characters);
there’s are also sub-menus covering autofocus sensitivity (high, medium or
low), auto white balance speed (fast, medium, slow, very slow), vertical and
horizontal phase adjustment -- when the camera is used with external synchronisation
-- and global reset, to return all
settings to their factory defaults. The final option on the main menu is a
preset function, used to store a complete set of adjustments, up to 20 presets
can be memorised, useful if the camera is going to be used in a variety of
different locations.
OPERATION
All of the menu commands and functions can be
accessed and controlled from a PC using an RS232 communications link. The generally
informative instruction book includes a detailed outline of the comms protocols
and commands, and an RS232 adaptor lead is included with the camera. This
facility makes a lot of sense, particularly if the camera is mounted in an
inaccessible location, where it may be difficult to gain access to the menu
buttons, and observe the results on a monitor at the same time. All of the
set-up procedures can be carried out remotely, using an ordinary laptop PC.
The large number of exposure and set-up
options, allied to the highly versatile lens means the camera can cope with a
very wide range of situations, and it is particularly well suited to life on a
motorised pan/tilt mount. The camera’s special talents have been capitalised
upon by Building Block Video (BBV) who have developed one of their control and
telemetry systems to work exclusively with the CCD-400. We took the opportunity
to try the system whilst we were testing the camera, the outfit comprises a
TX400 controller and transmitter unit, and specially modified RX300M telemetry
receiver.
The transmitter and receiver modules are
connected together by a single twisted pair, video is carried by coaxial cable,
routed via the two units. Unfortunately this arrangement is designed for composite-only
video and precludes the use of the higher quality S-Video connection, though it
should be possible to make alternative cabling arrangements. A specially made cable
carries power and control signals from the receiver to the camera.
In addition to fully programmable pan and
tilt control and ancillary switching (wash, wipe lights etc.), the BBV system
will also adjust the camera zoom, focus and iris, and access several of the
CCD-400’s menu functions. They include setting the shutter speed, white balance
and backlight compensation.
We were a little concerned to find that the
mains transformer inside the receiver unit had come adrift -- presumably during
transit -- and had been rattling around the inside of the case. Fortunately all
of the connections were intact, and the damage was limited to a bent mounting
lug. Interconnections are very straightforward, though the marriage between BBV
and Mitsubishi isn’t entirely successful. Some of the menu control functions outlined in the instruction book didn’t work as
described, luckily we managed to find the correct key combinations by trial and
error. One of the relays in the receiver box took to chattering every now and
again. External interference seemed a likely cause, though turning off all
nearby appliances and devices failed to silence the relay. Interrupting the
power supply to the transmitter control usually provided a temporary cure, the
exact cause was never found.
PERFORMANCE
One of the two CCD-400 cameras used in the
test exhibited what we assume was a minor software fault, with the iris locked
permanently in the auto mode, otherwise they behaved satisfactorily and
on-screen performance was generally very good. At the top speed setting the
zoom moves from wide to telephoto in just two seconds, that’s a good deal
faster than the AF system can cope with, and occasionally it failed to achieve
a lock at maximum magnification. The solution was back off the zoom, to allow
focus to regain lock. This tended to happen more at indoor lighting levels,
though the autofocus wasn’t especially responsive at the best of times, even
after fine-tuning the sensitivity. Nevertheless, zoom speed and power are
impressive with no loss of linearity or picture sharpness, at the either end of
the scale.
Resolution is up to spec, both of our samples
managed just under 400 lines on a composite feed, and well over 420 lines using
a Y/C connection. The exposure system is reasonably agile and can deal with
changes in lighting level quite quickly, the metering system is fairly crude and
bright lights within the scene area can adversely affect exposure. Backlight
compensation can come in quite useful, though it works best on static scenes.
The white balance system has enough control latitude to deal with most types of
lighting, and mixtures of natural and artificial light. Colour fidelity and
dynamic range are both good, noise levels are low, and that includes areas of
high saturation, though needless to say the amount of picture noise does
increase when light levels fall. At and around the 1 lux level the picture is
quite muddy and fine detail tends to become rather fuzzy.
OVERALL ASSESSMENT
In most situations the CCD-400 is a real
problem solver. It’s a compact design, that performs at least as well as most other
cameras in a similar price category, though it’s difficult to make too many meaningful
comparisons as this one comes with a lens, and a very sophisticated one at that.
Moreover, because there’s no external lens it takes up less room and fits into
spaces where ordinary cameras could not be used. The integral zoom lens takes good
care of lens selection on a fixed installation, though it’s primary role must lie
with a motorised pan and tilt platform, where its versatile lens and exposure
systems, plus the extensive range of remotely controllable functions, can be
put to very good use.
PRODUCT ASSESSMENT
Design and design features ****
Circuitry and components *****
Ease of installation and wiring ****
Range and variety of functions *****
Accompanying instructions ****
Technical advice and backup *****
Value for money *****
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Ó R.Maybury 1997 1411
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