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BAXALL CD900 CAMERAS (CD9252 & CD9312)
General-purpose CCTV surveillance cameras
have become something of a commodity item in recent years. Product development
has settled into a fairly predictable pattern of size and cost reductions with steady
improvements to both performance and facilities. Many of those trends are clearly
illustrated in Baxall’s CD9000 range of cameras. We’ve been looking at two of
them, the CD9252 and CD9312. These compact, well-specified mains-powered monochrome
and colour cameras are designed to meet the needs a wide range of applications
with low-light sensitivity, ease of installation, and flexibility high on the
list of features. Variants with universal low-voltage power supplies (12 v
DC/24 v AC), and slightly simpler specifications are also available.
Externally the two cameras look almost
identical. They have the same cream-coloured alloy outer casing with matching ABS
plastic end caps; excluding the lens they measure just 132 x 60 x 67mm. The
only distinguishing features are a coloured flash on the side of the CD9312 and
a second BNC socket on the back panel of the CD9252, for an external genlock
connection. The lens mounts accept a wide variety of optics, including 1/3,
1/2, 2/3 or 1-inch format C or CS lenses, with a fixed, manual, auto or
direct-drive iris. The back focus adjustment doubles up as the C/CS lens
setting, the setting is changed using one of a pair of recessed screws on the
top and side of the front cap; cameras are factory set for CS lenses. On both
models a female BNC connector on the back panel carries the standard 1-volt p-p
video output signal, additionally there’s a green power-on LED, adjustment for
line-lock phase, the captive mains cable and a 3-way spring-loaded clip terminal,
for an auto-iris lens.
A discreet hinged panel on the side of the
cameras opens to allow access to two banks of sub-miniature DIP switches and rotary
presets, for setting the various exposure options and level adjustment for an auto-iris
lens. Next to that, on the side of the case there’s a standard 4-pin square socket,
for a direct-drive auto-iris lens. Standard mounting threads (1/4 BSW or 1/4-in
BNC) are moulded into the top and bottom sections of the case.
The internal layout is similar on both
cameras. One third-inch Sony Hyper HAD interline transfer CCD image sensors are
mounted on a single board, on the back of the focus assembly; this is integrated into a cast alloy end plate. The
PCB connects by a short ribbon cable to the video processing and control board,
(the colour camera has a second daughter board, attached to the main PCB). The
mains PSU sits in the bottom of the case. A PCB mounted in the rear of the
camera supports the sockets and indicator LED, this is attached to a pressed-steel
sub-frame inside the end cap. The whole assembly is rigid and structurally very
strong, moreover the quality of construction of both the mechanics and the
electronics is of a very high order. The cases are not well protected against
ingress of dust, moisture or contaminants
and should be housed inside a protective case, if they’re going to be used in a
hostile environment.
The monochrome CCD image sensor inside the CD9252
has a 752 x 582 pixel array, giving a quoted resolution of 580 lines, with a low-light
sensitivity of just 0.1 lux (F1.2). Power consumption is in the order of
4-watts. Exposure adjustments include the option of white spot or backlight
compensation, for difficult scene illumination, switchable AGC and gamma
correction (0.45 or 0.8), manual or automatic high speed shutter (1/50th to
1/100,000 th. seconds, in 8 steps), selection of internal or line-lock
synchronisation and the preset for adjusting the line-lock phase.
The image sensor on the CD9312 also has a 752
x 582 pixel array, but low-light sensitivity is around 2.5 lux (F1.2) and
resolution falls to 460 lines. Power consumption is 5 watts. The range of
adjustments includes switches and presets for manual or automatic white balance,
backlight compensation, gamma correction, AGC, internal or line-lock
synchronisation and auto/manual high-speed shutter (1/50th to 1/100,000th sec).
Preliminary adjustments are confined to configuring
the camera to the lens and selecting the appropriate exposure and iris systems;
using the genlock connection on the mono camera puts it into external control
mode, overriding any other settings.
The DIP switches are very small; care -- and
a very small screwdriver or sharp implement -- is needed to alter the settings.
Unfortunately the microscopic switches can be difficult to see and get at,
especially if the camera is mounted in a confined space or with the control flap
facing a wall. The fairly brief instructions contains basic installation and
set-up advice but nothing in the way of performance data or detailed
compatibility information. Baxall have thoughtfully printed a helpline number
on the camera under the control flap, just in case it gets separated from its
instruction sheet.
PERFORMANCE
Low light sensitivity on the CD9252 proved to
be very close to the manufacturers specifications; it will produce a useable image in very poor conditions indeed,
though noise levels are quite high and there is a fair amount of grain in the
picture. Bright lights in the scene area do produce some vertical smearing but
it’s no worse than most other cameras of this type. Backlight compensation
works quite well, the spot-light function had only a marginal effect. In good
light the image is very clean, with plenty of detail; resolution on our sample
was approaching 550 lines. The auto exposure system copes well with gradual
changes in lighting levels, though it take a moment or two for it to compensate
for sudden fluctuations.
It’s a similar story with the CD9132, the
camera performed extremely well, within a whisker of the specification under
our normal test conditions. Low light sensitivity is more than adequate for
normal room or office illumination. Colour balance and accuracy are both
average to good. The auto system tends towards a slight yellowish caste when
the fluorescent tubes are the predominant light source, it fares much better in
mixed or natural lighting. Setting the white balance manually helps but if
there’s a change in the type of light (from natural to artificial, say) it may
drift slightly. Nevertheless, these changes are generally quite small and in
most circumstances there should be sufficient manual adjustment to reach a
satisfactory compromise. Once again the auto exposure system works well, with a
sufficiently wide range for the camera to operate with a fixed iris lens, in
situations where lighting levels change throughout the day.
OVERALL ASSESSMENT
These are two well designed multi-role cameras
with relatively few frills, no gimmicks and a realistic price. They’re
functional, solidly built and they perform well. The impressively wide range of
exposure and lens options covers the majority of routine surveillance
applications and should enable them to integrate easily with most single and
multiple camera set-ups.
PRODUCT ASSESSMENT
Design and design features 8
Circuitry and components 9
Ease of installation and wiring 8
Range and variety of functions 8
Accompanying instructions 7
Technical advice and backup 8
Value for money 8
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Ó R.Maybury 1996 1603
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