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MERIT LI-LIN PIH-7728PW METAL DOME CAMERA

 

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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.

 

PERFORMANCE

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.  

 

OVERALL ASSESSMENT

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 considering.

 

 

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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R. Maybury 2002 2811

 

 


 

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