What our experts say …
Up until a few years ago improvements in colour camera resolution used to occur on a fairly regular basis. However, following the appearance of realistically priced single chip colour cameras with the capability to resolve 400 or more lines, things seem to have slowed down. Over the past couple of years the numbers have crept up and 470-line colour cameras are not anywhere near as rare or expensive as they once were. But little apparent progress seems to have been made since then.
Clearly manufacturers can keep on expanding the CCD image sensor chip resolution envelope until the cows come home, but we seem to have reached a natural plateau, possibly as a result of camera technology outpacing recording systems’ ability to record fine detail and, to a lesser extent, the cost of high-performance colour monitors capable of displaying high-resolution images.
The arrival of the Sanyo VCC-6572 suggests that things could be on the move once again, and this inauspicious-looking little camera has a claimed resolution of some 520 lines. That kind of performance – previously only available on serious and often very specialised high-end imaging devices – raises the questions: who needs it, and how can you make use of it? On-going developments in other areas of the industry almost certainly provide the answers.
Firstly, the price of higher resolution CCD image sensors continues to fall to the point where it costs little or nothing extra to achieve 520-line performance. Secondly, and probably more significantly, devices that can record a 520-line image are becoming more readily available in the form of hard-disc and PC-based systems, digital VCRs and now recordable DVD.
From the outside it is not much to look at, surprisingly ordinary in fact considering that this is a cutting-edge product. The overall dimensions (excluding lens and mounting bracket) are 109 x 56 x 45mm and it weighs in at 310g (also without a lens). The feature list is also fairly sparse. The key points are that 520-line resolution figure, which is courtesy of a 1/3-inch 470k pixel interline CCD. Minimum low light sensitivity is just 1.0 lux (F1.2) and picture noise is an impressive 48dB.
Extensive use has been made of digital signal processing circuitry to automate exposure under a very wide range of conditions, however it does have a handful of manual functions. These include a variable speed shutter (1/50th to 1/10000th sec in steps), aperture compensation (sharp or normal), backlight compensation and white balance.
Additionally the camera can be configured for automatic iris or video/DC controlled auto-iris lenses and internal or external synchronisation. Adjustments are made from a 10-way miniature DIPswitch that is hidden behind a removable panel on the right side of the camera body.
At the front there is a standard CS mounting collar moulded into the ABS front panel. Two formed steel panels, top and bottom, complete the casework and the rear panel is part of the internal steel chassis. On the back there are two BNC sockets for video out and external sync, a five-pin mini DIN socket which carries the Y/C S-Video output, a single red power-on LED and a spring terminal for the 12v DC supply.
The only other features of note on the outside are a four-pin auto iris socket on the right side and a pair of screws for back-focus adjustment and lock on the left side.
Inside it is quite crowded with two large PCBs top and bottom (these handle video processing and power supply regulation) plus two smaller PCBs. One is for the CCD image sensor and support components. The other, mounted sideways on, is for the DIPswitch and trim pots for setting white balance, external sync phase and auto iris lens level adjustment.
Build quality appears to be very good indeed: wiring is kept to an absolute minimum and the construction is very solid. The case is not weatherproof but it should afford the internals very good protection against mechanical shock.
Set up & operation
Apart from the mechanical back-focus adjustments the camera can be left pretty much to its own devices in most situations. However, should the need for manual intervention arise, the DIPswitch and trim pots are all reasonably accessible, though the little screw that holds the access panel in place is microscopic and easily lost.
The only setting that might occupy you for more than a couple of minutes is backlight compensation. The camera has two separate modes, multi-spot photometry and centre-focus photometry.
In the ‘multi’ mode the screen is divided into 64 zones and backlight compensation is applied to the whole screen area. In the ‘centre’ mode compensation is only applied to the central portion of the image. White balance is normally best left to the electronic minions; however, in difficult lighting conditions the relative red and blue levels can be tweaked. The mounting bracket can be attached to the top or bottom panels.
Performance
If camera resolution increases much further we may have to start re-thinking our test procedures and equipment. However we were able to ascertain that the our sample VCC-6572 was indeed able to resolve a little in excess of 500-lines, producing a pin-sharp image that in good light has almost insignificant amounts of picture noise.
It looks really clean and colours are crisp, very well defined and very natural looking in daylight lighting conditions. The exposure and auto white balance systems are both reasonably responsive and it copes well with sudden and gradual changes in lighting level and lighting mixtures. In any event we felt there was no need to make any manual adjustments. The image is rock-solid and did not waver when the case was treated to a few hefty thwacks with the highly scientific Bench Test rubber mallet.
What the manufacturer says …
Sanyo has always been at the forefront of technical developments within the CCTV industry but we are particularly proud to be the first manufacturer to introduce a single chip camera that offers 520 TV lines horizontal resolution. The VCC-6572P 1/3-inch colour camera has a revolutionary DSP circuit which incorporates a host of technical innovations. Collectively these innovations result in a camera that offers customers images of clarity that have never previously been available for standard CCTV systems.
The new single chip DSP circuit employed in the VCC-6572P offers an extremely sophisticated backlight com-pensation function, colour reproduction and aperture compensation which com-bined, produce a comprehensive improve-ment in picture quality.
Sanyo has written new algorithms specifically to allow the VCC-6572P to reproduce natural colours, reduce smear and produce sharp, crisp pictures. The advanced backlight compensation utilised by the VCC-6572P provides a clear picture of off-centre and moving subjects. The innovative method used eliminates the shortcomings of conventional backlight compensation by dividing individual frames into 64 small areas in which luminous intensity is measured separately to determine the lighting conditions of all objects within the frames.
