The bench test 1: Hey, good looking

Apart from the odd wackily shaped or coloured camera, 'designer' culture has had a negligible impact on video security and surveillance products. Form has always been subordinate to function, and rightly so, but every so often we see a device that suggests someone has spent more than five minutes thinking about how it looks.

The highly distinctive Cohu 3960 series PTZ camera definitely falls into that category and follows a recent cosmetic trend for equipment with softer, more rounded profiles.

But it's what's inside that counts and in that respect the 3960 has a few more surprises in store. Several versions are available; the one we've been looking at is a top of the range pedestal mount model with a day/night camera (with switchable UV filter) coupled to a 35x optical zoom.

The side-mounted camera module sits inside a smoothly contoured sun shield. It is a sealed and pressurised design based around a 1/4-inch Interline CCD with 768 x 494 pixels giving a claimed resolution of 520 lines. Low light sensitivity is between 1 lux (colour mode) and 0.01(mono night mode and 1/4 sec shutter). This particular model also features electronic image stabilisation (EIS) plus a 12x digital zoom, various user programmable IDs, an on-screen compass or position display and up to eight privacy zones.

According to the specs positional accuracy in preset mode is in the order of 0.1 degree and it's no slouch with the pan/tilt mechanism, reaching speeds of up to 160 degrees/sec. The camera tilts through +/-90 degrees and pans continuously through 360 degrees giving it a full all-round view. Up to 16 horizontal 'zones' can be defined and it can store a maximum of 64 preset positions (including zoom and focus settings). These can be used to program up to eight Tours, each comprising up to 32 positions, with independently selectable dwell times for each preset.

Camera and PTZ operations are PC controlled using a Windows program called WinMPC, which uses proprietary protocols and serial communications to communicate with the camera. It has a slightly old-fashioned feel to it and one or two odd quirks but more about those in a moment.

Under pressure

Sealing and pressurising the camera (with inert nitrogen gas) is a highly effective way of keeping out contaminants, moisture and bugs, and this also explains why there is what looks like a car tyre valve and a safety valve on the rear of the camera. In fact these are about the only external features and on the front there's nothing to see except a window protecting the lens. The almost featureless positioner casing also gives nothing away and the power, video output and telemetry connections are combined into a single cable that emerges through the base; this is terminated in a weatherproof Amphenol connector.

The heavy-duty, two-part cast alloy case is IP67 rated. Inside the PT mechanism is built around the central bearing. The two motors are bolted to a very substantial aluminium chassis, which also provides mounting points for a PCB responsible for power supply and motor control. The two motors transmit motive power through a pair of toothed belt and pulley gearboxes.

Build quality and the materials used are of an exceptionally high standard, almost to the point of it being over-engineered. Needless to say this is an application where reliability and endurance are of paramount importance and all the evidence suggests that this camera will be able to withstand the worst that nature (and man) can throw at it.

Setup and operation

Cohu’s i-view II 3960 PTZ camera looks attractive on the outside, but how does it match up when it comes to functionality and performance?

Installation, apart from fixing the camera into position, is unlikely to cause any problems, since there are no external controls or adjustments. Connections to the outside world comprise a 24v AC power supply, video output and telemetry, the latter via a PC serial port (or USB to serial adaptor).

WinMPC is a self-contained program – it requires no installation and the executable file only has to be copied to the PC's hard drive. Once the program is launched it seeks out the camera and after a brief 'handshake' the two devices are connected in what is effectively a closed loop.

There's no need for the kind of security normally found on PTZ cameras controlled through a network, but even so we were a little surprised that no attempt has been made to restrict access to the program by PIN or password, and there's no way to protect configuration settings from accidental or deliberate alteration.

The main screen is dominated by the pan/tilt 'control' in the centre. The shape and background graphic can be changed but we prefer the 'globe' design asome of the more colourful designs actually make it quite difficult to use. In fact the whole thing takes a little getting used to but once you've figured out that it is basically an on-screen 'joystick' it starts to make sense and reasonably easy to use.

Above the joystick are the main camera controls (zoom, focus, iris etc) and below and to the right are the positioner settings, preset and tour programming controls. Various secondary and pre-set functions are accessed through buttons, which lead to sub menus or dialogue boxes.

The Privacy Mask facility is a real hit and miss affair that takes a fair amount of patience to master. Privacy mask systems normally work by positioning and sizing variable sized opaque rectangles on to the image but this camera simply blanks the picture between preset (horizontal) angles, which basically means it is virtually impossible to mask out relatively small areas or objects, like windows or bright lights.

Performance

Picture quality is excellent. The camera is clearly a high-performance design and it copes almost effortlessly with wide variations in lighting level. Resolution on our sample is approaching the manufacturer's figure and picture noise in normal daylight is very low and remains well controlled as light levels fall.

Night/day switching is fast and well timed to coincide with changes in the noise present in the colour image. Nevertheless some form of manual override or adjustment could prove useful, as would some sort of backlight control. The auto exposure systems are effective but once or twice our sample over-reacted to a very bright light or reflection at the edges of the image.

Pan and tilt action is fast, smooth and capable of precise adjustment. However, as far as we could see there's no provision to link PT action to camera zoom so at higher magnification levels it becomes increasingly difficult to control the camera position with any degree of accuracy.

A small inadvertent movement of the mouse can easily cause the operator to loose track of a distant subject or object. There are a number of pan and tilt control options in the Camera Setup sub-menu but we couldn't find one to link it to the zoom – and the instruction manuals are none too helpful on this score – and moreover despite several attempts, our efforts to change speed settings or presets failed as it always reverted back to the defaults.