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Choosing the most appropriate lens for a video surveillance camera has developed into something of a black art. Whilst there are all kinds of helpful formulae, charts and tables, a lot of the time it comes down to the installerís experience and the price the end-user is prepared to pay. The Mitsubishi CCD-400 colour video camera effectively overcomes most of the complications concerned with lens selection, opens up a range of alternative possibilities and solves a several other commonly encountered problems, into the bargain.  


The camera uses an 0.25-inch CCD image sensor with a total of 440k pixels (effective), the stated low light sensitivity is down to 1 lux (maximum gain) and resolution is quoted at 430 lines, using an S-Video connection.  To be honest itís not much to look at, an anonymous little black box just about sums it up. It measures 66 x 55 x 104 mm and apart from the colour, it looks like a dozen other compact surveillance camera bodies, except that this one isnít just a body, itís the whole camera, lens and all. Where you would normally expect to find a lens mounting collar is the front optical element of a miniature motorised zoom lens assembly, with autofocus and mechanical iris facilities built in. This sort of all in one design is not exactly a new idea, in fact the CCD-400 is a development of the similarly configured Mitsubishi CCD-200, Bench Tested right here in 1995. Then, as now, it is built around a self-contained inner-focus zoom lens assembly, similar to the types used on domestic camcorders. The new camera has an increased zoom range, up from 8X to 14X; it also has a wider range of manual and automatic exposure functions, and external control facilities, designed to allow it to be used with a PC or proprietary telemetry and control systems. Weíll come to that in a moment, but first a closer look how the camera has been put together.


The large lens dominates the front of the camera, the lens surround is fitted with a 46 mm threaded collar, designed to take a screw-on filter. This will both protect the lens, and could come in useful in tricky lighting conditions. The sides and top of the case are mostly bare; a mounting plate with a standard threaded boss is fitted to the underside of the case, itís held in place by four small screws and can be moved to the top of the case, if required. In contrast the back panel of the camera is very busy indeed. Thereís a fair few sockets; two BNC connectors handle composite video out and external sync in. It has two mini DIN sockets; a 6-pin type handles S-Video (Y/C) output, and below that thereís a 9-pin socket which is used to carry RS-232 data. Lastly thereís a 3.5 mm power input socket for the 12 volt DC supply; a suitable  plug-in mains adaptor is available from Mitsubishi as an option. There are only four controls: three buttons and a miniature slide switch, that between them, control a commendably wide range of functions


The steel case is in two halves, inside thereís what amounts to an exoskeleton chassis, with printed circuit boards mounted on the inside of the frame, surrounding the barrel-like lens mechanism. Access to the lens is very restricted, hopefully it shouldnít become necessary. The case is reasonably well protected against the ingress of dust or moisture, though it is only rated for indoor use, in a normal operating environment.


All of the cameraís lens and exposure functions are controlled from a set of menu-driven on-screen displays, using the three buttons on the rear of the case. The buttons also act as manual controls for setting the zoom, iris and white balance, without having to delve into the menu.


The on-screen display is a good place to begin a tour of the various functions. The first page of options begins with the lens, this leads to a second sub-menu covering zoom and focus functions. There are four zoom speed settings and a choice of auto or manual focus. The brightness menu calls up sub-menus for setting manual or auto iris and video gain. The third option is for adjusting backlight compensation. Menu option four is for setting the electronic shutter, there are 8 speeds, between 1/50th and 1/10,000 th. second. Next is the detail or sharpness control, presettable in 15 steps. The colour menu has settings for white balance lock, (auto, indoor, fluorescent, sunlight and fixed) plus adjustments for R-Y and B-Y gain and hue.


The second page of menu options includes a simple character generator, used to create a camera ident (up to 8 characters); thereís are also sub-menus covering autofocus sensitivity (high, medium or low), auto white balance speed (fast, medium, slow, very slow), vertical and horizontal phase adjustment -- when the camera is used with external synchronisation --  and global reset, to return all settings to their factory defaults. The final option on the main menu is a preset function, used to store a complete set of adjustments, up to 20 presets can be memorised, useful if the camera is going to be used in a variety of different locations.   



All of the menu commands and functions can be accessed and controlled from a PC using an RS232 communications link. The generally informative instruction book includes a detailed outline of the comms protocols and commands, and an RS232 adaptor lead is included with the camera. This facility makes a lot of sense, particularly if the camera is mounted in an inaccessible location, where it may be difficult to gain access to the menu buttons, and observe the results on a monitor at the same time. All of the set-up procedures can be carried out remotely, using an ordinary laptop PC.


The large number of exposure and set-up options, allied to the highly versatile lens means the camera can cope with a very wide range of situations, and it is particularly well suited to life on a motorised pan/tilt mount. The cameraís special talents have been capitalised upon by Building Block Video (BBV) who have developed one of their control and telemetry systems to work exclusively with the CCD-400. We took the opportunity to try the system whilst we were testing the camera, the outfit comprises a TX400 controller and transmitter unit, and specially modified RX300M telemetry receiver.


The transmitter and receiver modules are connected together by a single twisted pair, video is carried by coaxial cable, routed via the two units. Unfortunately this arrangement is designed for composite-only video and precludes the use of the higher quality S-Video connection, though it should be possible to make alternative cabling arrangements. A specially made cable carries power and control signals from the receiver to the camera.


In addition to fully programmable pan and tilt control and ancillary switching (wash, wipe lights etc.), the BBV system will also adjust the camera zoom, focus and iris, and access several of the CCD-400ís menu functions. They include setting the shutter speed, white balance and backlight compensation.


We were a little concerned to find that the mains transformer inside the receiver unit had come adrift -- presumably during transit -- and had been rattling around the inside of the case. Fortunately all of the connections were intact, and the damage was limited to a bent mounting lug. Interconnections are very straightforward, though the marriage between BBV and Mitsubishi isnít entirely successful. Some of the menu control functions outlined  in the instruction book didnít work as described, luckily we managed to find the correct key combinations by trial and error. One of the relays in the receiver box took to chattering every now and again. External interference seemed a likely cause, though turning off all nearby appliances and devices failed to silence the relay. Interrupting the power supply to the transmitter control usually provided a temporary cure, the exact cause was never found.



One of the two CCD-400 cameras used in the test exhibited what we assume was a minor software fault, with the iris locked permanently in the auto mode, otherwise they behaved satisfactorily and on-screen performance was generally very good. At the top speed setting the zoom moves from wide to telephoto in just two seconds, thatís a good deal faster than the AF system can cope with, and occasionally it failed to achieve a lock at maximum magnification. The solution was back off the zoom, to allow focus to regain lock. This tended to happen more at indoor lighting levels, though the autofocus wasnít especially responsive at the best of times, even after fine-tuning the sensitivity. Nevertheless, zoom speed and power are impressive with no loss of linearity or picture sharpness, at the either end of the scale.


Resolution is up to spec, both of our samples managed just under 400 lines on a composite feed, and well over 420 lines using a Y/C connection. The exposure system is reasonably agile and can deal with changes in lighting level quite quickly, the metering system is fairly crude and bright lights within the scene area can adversely affect exposure. Backlight compensation can come in quite useful, though it works best on static scenes. The white balance system has enough control latitude to deal with most types of lighting, and mixtures of natural and artificial light. Colour fidelity and dynamic range are both good, noise levels are low, and that includes areas of high saturation, though needless to say the amount of picture noise does increase when light levels fall. At and around the 1 lux level the picture is quite muddy and fine detail tends to become rather fuzzy.



In most situations the CCD-400 is a real problem solver. Itís a compact design, that performs at least as well as most other cameras in a similar price category, though itís difficult to make too many meaningful comparisons as this one comes with a lens, and a very sophisticated one at that. Moreover, because thereís no external lens it takes up less room and fits into spaces where ordinary cameras could not be used. The integral zoom lens takes good care of lens selection on a fixed installation, though itís primary role must lie with a motorised pan and tilt platform, where its versatile lens and exposure systems, plus the extensive range of remotely controllable functions, can be put to very good use.   



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 1997 1411



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