SSC-DC50AP

Sony has developed a radical approach to the increasing demand for colour images in poor lighting by addressing the sensitivity of the actual image sensor used within the camera. On chip lens (OCL) technology has been very effective in improving sensitivity by locating a microlens on each pixel which results in more light being collected on the photosensitive layer.

Sony has now taken this technology further with the development of the SSC-DC50AP camera series which utilises a still more advanced OCL CCD structure – ExwaveHAD. By optimizing the configuration of the microlenses, the ineffective areas between them are significantly reduced – a 'gap-less' structure.

Light loss is minimized and more use is made of the light that is available. The result is a degree of sensitivity that can effectively handle light levels as low as 0.8 lux (F1.2, 50IRE) and still deliver a clear colour image even with rapidly moving objects. Vertical smear is caused by the leakage of unwanted light onto the vertical shift register. The SSC-DC50AP camera series reduces this leakage dramatically because the improvement in the cell structure minimizes the undesirable reflection of light onto the CCD surface. The effect is a reduction in smear which is 50 times better than that found with other CCDs. The level achieved with the SSC-DC50AP camera series of –120dB is in fact comparable to that of FIT (Frame Interline Transfer) CCDs which are used in broadcast cameras.

Together with the range of other features such as automatic and programmable backlight compensation, line-driven power facility and choice of lens formats, the camera therefore lends itself to a wide range of applications, including car parks, traffic monitoring, business parks, town centres and general security surveillance where lighting can be sub 1 lux and where colour real-time images are sought. All aspects of Sony camera manufacture and components are quality assured, subject to ISO9000 standards, and all cameras carry a three year manufacturer's guarantee.

(Please note "ExwaveHAD" is trademark of Sony Corporation.)

WHAT OUR EXPERTS SAY...

The dramatic growth in the size of the market for inexpensive board cameras is clearly a very welcome development and some of them are very good indeed but it has tended to obscure the fact that there are still plenty of applications where performance, rather than cost, is the main consideration. Cheap compact cameras are perfectly adequate for a lot routine applications but their inherent limitations quickly become apparent when they are faced with difficult or demanding situations.

There will always be a steady demand for top quality cameras that can react and respond to big or sudden changes in illumination and still deliver a sharp image in poor light and this is a market that Sony has targeted with its ExwaveHAD models. Currently there are three colour cameras in the range, the SSC-DC50AP, which we are looking at here, the SSC-DC54AP and the SSC-DC58AP.

The principle differences involve the camera's power supplies. The DC50 has the option of single cable wiring with the coax carrying video, DC power and sync (when used with YS-W150 or W250 camera adaptor units) or it can be powered from a separate 12 volt DC supply; the DC54 requires a 24 volt AC supply and the DC58 is mains powered. Apart from that, and some relatively small variations in the casework, they are virtually identical.

The key feature, common to all three cameras, is the ExwaveHAD CCD image sensor. Sony claims the new chip has twice the sensitivity and significantly reduced smear, compared with conventional HyperHAD CCDs, such as those used on the SSC-DC50P/54P cameras. The improvements have been brought about by a change in the design of the on-chip lenses or OCLs, which surmount each and every picture element or 'pixel' on the surface of the chip. On the new OCL, gaps between the micro lenses have been virtually eliminated, allowing more light to pass through to the light sensitive layer below.

Further changes to the structure of the surface of the chip has resulted in fewer internal reflections and smear reduced by a factor of 50. The bottom line is a claimed low-light sensitivity of 0.4 lux at F1.2.

While we are looking at the specs, other notable numbers include a horizontal resolution of 470-lines from the ½-inch CCD, which has a 752 x 582 pixel array. The signal to noise ratio is a very respectable 50dB and it has a manual electronic shutter with eight-speed settings (1/50, 1/120, 1/250, 1/1000, 1/2000, 1/4000, 1/100 000th second).

Needless to say it has fully automated exposure controls and options as well. They include automatic shutter speed (CCD iris) adjustment and a two-mode AGC (turbo or normal), with the turbo setting controlling video gain over a wider than normal range of 0 to 24dB. Smart Control is a clever facility that optimises gain and iris controls to achieve more effective backlight compensation.

It is possible to make the camera even more responsive with a facility that splits the screen into seven detection areas. The camera has a sophisticated white balance system, with four operating modes: 'Advanced' shares some of the Smart Control functions. It is meant for conditions that change frequently, and covers a range of 2500 to 6000 K.

The auto tracing white balance mode (ATW) has a full coverage extending from 2000 to 10000 K. AWB mode stores white balance settings manually when the AWB button is pressed and there is a fixed 5600 K preset, for outdoor day-time operation.

The three cameras share a common chassis and are used with fixed or auto iris lenses (DC or video control) with C or CS type fittings. Back focus and lens adjustment is handled by a large thumbwheel protruding from slots in the top and bottom of the casing.

Externally the DC50AP and DC54AP measure 57 x 64 x 137mm. The DC58 is a little longer at 162mm, to accommodate the on-board mains PSU. The front of the camera is made from cast alloy. The centre portion is a two-part steel case and the rear panel is made from ABS plastic. A mounting panel with a standard ¼-inch threaded collar can be screwed to the top or bottom panels.

On the left side of the camera body is a standard square four-pin auto iris socket and a locking screw for the back-focus adjustment. In the centre of the panel there is a recessed eight-way mini-DIP switch. This is responsible for selecting AGC mode, backlight compensation on/off, auto/manual shutter, white balance mode, aperture control (normal/sharp) and SC phase control (when used with external synchronisation).

Below the DIP switch is a two-position slider for selecting auto iris lens type (DC or video controlled) and to the right of that are two rotary presets (shutter speed, SC phase), and the button for setting auto white balance.

There are two more rotary controls, AE Spot switches between the sensitivity zones and below that is a preset for adjusting horizontal/vertical phase shift. The controls and the PCB beneath are exposed to the elements via the slots in the side panel so the camera is not suitable for use outdoors or in any kind of hostile (damp, dusty) environment without adequate protection.

On the back panel there are two BNC sockets. One carries the video output, DC supply and sync input, while the other socket is for a local monitor. Additionally the camera has a Y/C (S-Video) formatted video output and a two-way screw terminal for an external power supply. There are also two small slide switches, for selecting power supply mode and selecting S-Video output, plus a green power-on LED. Inside the case there are no less than four densely populated glass-fibre PCBs, bolted to a sturdy steel chassis. The power supply and regulation components on the lower PC are heavily screened, contributing to the impression that the device is built to a very high standard indeed. Interconnections between the circuit boards are kept to a minimum and mostly handled by ribbon cables, which look as though they have been positioned with a view to easy servicing.

In true Sony style the brief instruction sheet supplied with the DC50AP assumes a fair amount of familiarity with the concepts of installing and setting up CCTV cameras. It does little more than run through the controls and the various connection options, and rounds off with the technical spec. Fortunately it is all quite straightforward, though it is a good idea to spend a few minutes with the camera, before bolting it onto its mounting bracket, to get to know how to set the auto iris, shutter and white balance, as the DIP switches and rotary controls are very small and could be difficult to get to when the camera is in position.

The back focus thumbwheel is smooth with a slow, progressive action that makes precise adjustments very simple. The seven-stage detection zones (used for more responsive auto backlight compensation and white balance adjustment) have been well thought out. When the rotary switch is turned a semi-transparent white rectangle (denoting the area of sensitivity) appears briefly on the screen.

This also highlights the value of the second video output, for a local monitor, which should help make some installations a lot quicker and easier. Despite the brevity of the instructions, most experienced installers should have little or no difficulty with this camera.

Our sample performed more or less as advertised with resolution, noise and low-light sensitivity figures on or very close to the manufacturer's specifications. However, what the numbers do not tell you is that the picture from this camera is one of the cleanest and sharpest we have seen in quite a while with excellent colour fidelity and an impressively fast response to changes in lighting conditions.

It has an unusually wide dynamic range, revealing unexpected detail in dark areas and shadows, but it is the exposure system's flexibility and ability to cope with awkward situations that really sets it apart. It is capable of delivering a crisp, well-defined image in circumstances that would render many ordinary cameras useless.

It is exceptionally well built too and the picture on our line-powered sample never missed a beat, even when subjected to a good seeing to with the Bench Test rubber mallet.