MERIT LI-LIN PIH-7728PW METAL DOME CAMERA
WHAT OUR EXPERTS SAY...
Describing the PIH-7728PM as a dome camera might be stretching things
slightly though to be fair it is a very unusual design and difficult to know
exactly what to call itÖ Our suggestion would be an Ďeyeballí camera, though we
suspect someone somewhere may already have used the name, but it sums up quite
neatly how the camera looks and works.
The 7728 is a very specialist design that is meant to be installed in
suspended or false ceilings and if itís noticed at all it, it looks a lot like
a small spotlight. In theory it could also be wall mounted, though that would
depends on the wall, and how easy it would be to accommodate the rear of the
assembly and cables, which extend at least 4cm behind the mounting plate.
Inside the 6cm diameter hollow alloy sphere there is a board camera
module, the ball is sandwiched between two plates so that when the three fixing
screws are slackened, it is able to tilt through almost 180 degrees and pan
through 360 degrees. An outer trim bezel is supplied, which hides the mounting
plate. This is a bayonet type fit so there are no exposed screws or fixings and
it gives the appearance of being reasonably vandal-proof.
Various camera configurations are available; our sample was a colour
model, fitted with an F2.0, 3.6mm lens, in front of a 1/3-inch Sony Hyper HAD
CCD image sensor. This has a 752 x 583 pixel array giving a claimed resolution
of 480 lines and low light sensitivity of 1 lux. Monochrome camera modules are
also available and thereís an optional 6mm/F1.8 lens for both types. There are
no external controls or connections and a twin cable emerges from the rear of
the camera ball, approximately 28cm in length. This is terminated with an
in-line BNC socket carrying the composite video output signal, and a 2.5mm
connector for the DC power supply. The cable on our sample had no anti-strain
protection and we suspect that a sharp tug or drop could easily damage the
wiring or the small PCB mounted plug that itís attached to. It may be worth
putting a cable tie around the cable inside the ball to prevent this happening,
though this is something the manufacturers should take care of as a matter of urgency.
A 12-volt DC plug-in type mains adaptor is supplied with the outfit, along with
mounting plates and spacer, fixing screws and some rudimentary instructions.
Once the sphere is removed from the circular mounting plates it splits
apart with a light twist. The actual camera module is made up of two small
boards, both heavily populated with surface mounted components. The front
board, which has the image sensor and lens, is screwed to a circular plate that
ensures it is firmly seated inside the sphere; the front of the lens barrel
protrudes through a hole in the front. The second board is held in place by two
multi-pin connectors and when assembled the whole thing appears to be quite
rigid. The quality of construction and finish both appear to be very good; the
metal casing and mounting should prove durable. Itís not weatherproof though
and is designed for interior installation only.
SETUP AND OPERATION
The rearmost of the two camera boards has a 4-way miniature DIP-switch,
which is used to set the cameraís AGC and white balance. The options are 8 or
32dB variable gain and auto-tracing white balance or preset switch positions
for indoors, outdoors, fluorescent, plus manual set etc. There are no other
adjustments, though it is possible to remove the whole module from the front
half of the sphere to access the lens and fine-tune the focus.
In most cases installation should be reasonably painless, itís no more
difficult to fit than a ceiling panel lighting module, though aligning the
camera, when it is in position, can be quite tricky. Thatís because a thin
rubber O-ring between the mounting plates prevents the sphere from moving
smoothly; if youíre not careful it seizes completely and the bottom plate has
to be removed to free it up.
The ball gets surprisingly warm after just a few minutes of operation,
probably because it is sealed and thereís nowhere for the heat to go. It never
gets worryingly hot so it shouldnít be a problem though itís probably a good
idea to make sure it is sited in a well-ventilated position.
Resolution is not too far off the makerís spec and our sample managed
over 450 lines on our test charts without any problem. Claims for low light
performance are possibly just a tad optimistic though, and at very low light
levels the picture rapidly descends into a noisy mush. Nevertheless in good
light the picture looks sharp and detailed and if trouble is taken to set the
white balance Ė if itís going to be used in difficult conditions -- colours are
reasonably accurate. The auto exposure system responds quickly to changes in
light level though it has only limited abilities when it comes to dealing with
backlit subjects or scenes or bright lights in the scene area. The camera
module is stable and largely immune to mechanical shock.
Itís a well thought out design thatís unobtrusive and blends in well with
the type of dťcor found in many modern offices and retail premises. It is
keenly priced for a specialist camera, video performance in undemanding
lighting situations is very good and apart from some small misgivings about the
security of the power and video cable and the awkward alignment, both
installation and operation are both very straightforward. Well worth
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 ****
„ R. Maybury