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HTC-383 VIDEO CAMERA
COPY
Reports and articles detailing the numerous advances
being made in CCD imaging technology have tended to concentrate on developments
relating to high-end colour cameras and systems, but there have been some equally
significant improvements to humbler monochrome cameras, which after all still
form the backbone of the video surveillance industry.
Most of the development work has centred on
making these cameras smaller, with better low-light performance, increased
flexibility and facilities, moreover higher levels of component integration has
resulted in improved reliability, and lower prices. The HTC-383 CCD camera,
which is imported by Direct CCTV Ltd,
neatly illustrates virtually all of these points.
The HTC-383 is an exceptionally compact design,
the black extruded alloy case measures just 138 x 46 x 40mm, with an all up
weight of just 379 grams (without a lens attached), and judging by the amount
of empty space inside it could have been even smaller than that! The 1/3-inch
CCD image sensor has a pixel count of just over 290,000 with low light
performance rated at just 0.3 lux (f1.4). These impressive specifications are
all the more remarkable considering the unit price is now only £90, (down from
£100 in the last few weeks), or £126 with an optional Computar 4mm f1.2
non-iris lens.
The camera is DC powered though it doesn’t
come with a power supply as standard. Direct CCTV can supply a heavy duty 12
volt DC mains adaptor from Maplin for around £7.00, which is very good value,
though it has to be said this particular module is rather large, the DC cable
is only a couple of metres in length and the combination plug that fits into
the back of the camera adds almost 60mm to the overall length of the camera. An
AC powered version is mentioned in the instructions though Direct CCTV say they
have no plans to import this model at the moment.
Inside the case there are three PCBs. The
largest one which slots into rails running the length of the housing carries
most of the video processing microchips, (predominantly made by Sony). The two
smaller boards are bolted to the caps at either end of the case. The board at
the front supports the CCD image sensor and its associated driver components; the
one on the back panel incorporates sockets for video output (BNC), DC supply, the
supply and control connections for an auto iris lens (standard square 4-pin),
plus a miniature DIP switch for setting gamma correction (1/0.45) and enabling
the camera’s electronic iris. The camera has an electronic shutter which is
adjusted automatically, according to the amount of light falling on the image
sensor chip; the shutter varies in speed from 1/120 to 1/10,000th of a second.
The main PCBs make extensive use of surface
mounted component (SMC) technology, which saves a great deal of space, and
makes the whole assembly light and extremely rugged. Although the camera isn’t
specifically billed as a weatherproof design it is quite well protected against
the elements, there are no ventilation slots or holes that would allow moisture
and dirt to get inside. The importer claims to have accidentally dropped one
sample from a height of almost two metres without damage, we didn’t replicate
that particular test but it certainly looks as though it has been built to
survive in a harsh environment.
Both end caps are made from a lightweight cast
alloy; the one at the front has an integrated mounting bracket with a standard
1/4-inch thread, in addition to the CS lens mounting collar. Rotating the
collar gives a small amount of fore and aft adjustment, for setting back-focus.
Once aligned the collar is held in position by tightening a grub screw in the
base of the cap. An Allen key is supplied for this purpose, along with a screw-in
C-mount adaptor ring and an auto-iris plug. The accessory pack also contains a
second external mounting block; this attaches to two threaded holes on the top of
the case, using a pair of supplied bolts.
Apart from the two DIP switches on the back
there are no external adjustments. The very brief instructions make no mention
of gamma correction and simply recommend the electronic iris should be switched
on, or an auto iris fitted, if the scene illumination is likely to vary
throughout the day, or if the camera is going to have to cope with scenes that
experience sudden extremes of illumination
(car headlights etc.). Advice for installers is scant, there are some
basic guidelines for adjusting the lens, not subjecting the camera to
vibration, shock or extremes of temperature etc., but after that it’s left
pretty much up to the installers common sense.
PERFORMANCE
The low light figure of 0.3 lux, quoted in
the manufacturers specifications, is in line with the results obtained under
test conditions. So too is the horizontal resolution of 380 lines, though this
does depend on the use of a good quality lens; the optional 4mm lens is best
suited to fairly undemanding situations. Picture noise levels are commendably
low, even in quite poor light. Although the automatic exposure system is quite
basic, it can compensate for a reasonably broad range of lighting conditions.
It responds fairly slowly to rapid changes in lighting level though, and care
needs to be taken during installation and alignment to avoid bright lights
within the image area or strong backlighting, otherwise the electronic iris
tends to over-react and the image can be washed out.
OVERALL ASSESSMENT
The automatic iris and exposure system is
relatively unsophisticated, compared with what’s now appearing on middle and
top range cameras, though it’s perfectly capable of dealing with most routine
situations. The 383’s low light
capability and resolution figures are not in themselves all that unusual,
though this level of performance is rarely, if ever seen on cameras as small
and inexpensive as this one.
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 1995 0404
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