The bench test 1: The Rainbow connection

What our experts say…

Video cameras tend to be quite hardy beasts, and provided the electronics and optics are well protected against damp, dust and physical shock, they can operate in a surprisingly varied range of atmospheric and environmental conditions.

Nevertheless, Rainbow is taking no chances with the OLC 48VD5HX outdoor colour camera, and in addition to the very sturdy weatherproof housing, the internal components enjoy the additional benefits of a controlled microclimate that cools them down when it gets too hot and warms them up when it gets a bit chilly.

At the heart of the camera is a 1/3 inch Sony Super HAD CCD image sensor with a low light sensitivity of 0.7 lux, and the 752 x 582 pixel matrix gives a claimed resolution of 480 lines.

In front of the sensor there's a 5-50mm DC type auto iris lens with manually adjustable focus and tele-wide settings. Although the exposure options are a tad limited in comparison with some rival designs, it does have a set of manual and automatic white balance controls, backlight compensation and switchable auto iris/electronic shutter operation. There's also the option for internal or line-lock sync and a 'flickerless' mode for use with tube lighting.

It looks tough and well engineered; the body of the camera is basically a three-part alloy cylinder with a thick glass window at the front, protecting the lens.

At the rear there are two industrial grade Amphenol screw-fit sockets finished in military style Olive Drab. One handles the power supply feed (24VAC or 12VDC); the other carries the standard composite video output. On the top of the casing there is a mounting bracket with standard 1/4-inch thread. The moulding incorporates grooved guides for the detachable and adjustable alloy sunshield. The main mounting point for the camera is located on the underside at the rear of the body.

The camera's internal temperature is controlled by sensors linked to a cooling fan and a heating collar that fits around the lens assembly. The fan draws in filtered air and blows it out thorough a ventilation port between the lower mounting points. Incidentally, the heater only operates when the camera is powered from a 24VAC supply.

Access to the setup controls and lens is achieved by unscrewing the front portion of the housing; rubber gaskets provide a secure weatherproof seal. The heating collar sits loosely inside the cylinder barrel and it has to be unplugged before the cover can be fully withdrawn. Once it has been removed the lens assembly and circuit board containing the setup controls are exposed.

Inside there are three circular PCBs. The front one supports the image sensor, lens and controls, the other two are responsible for video processing, power supply and ancillary functions. The controls comprise an eight-way miniature DIP switch, for selecting setup functions, a pair of push buttons are used to set white balance and line-lock phase adjustment, a small slide switch to selects Video or DC auto iris operation, and below that is a trimmer for setting the DC iris level.

The controls are small and uncomfortably close to components and connectors on the circuit board so extreme care needs to be taken to avoid touching anything when carrying out adjustments.

Setup and operation

Once the camera has been mounted and aligned the first job is to set the lens focus and field of view using two small lockable arms on the body of the lens. For some reason the lens on our sample was loose, and before we could make any adjustments it was necessary to disconnect the auto iris cable and re-tighten the mounting thread.

Rainbow's OLC 48VD5HX Outdoor Colour Camera has almost impreccable credentials

Bearing in mind that this is an 'outdoor' camera and therefore designed to operate over a wide range of lighting levels it would be fair to assume that exposure can be safely left in the hands of the auto systems; however, as we shall see in a moment, some tinkering with the controls may well be necessary.

In contrast, the camera's auto white balance system is unusually efficient, and we suspect that in most cases intervention will not be necessary, yet Rainbow have provided the camera with an unusually extensive set of manual controls. For the record, in addition to full auto WB, extra options include presets for 3200, 4200, 4700 and 6300 degrees K, adjustable red/blue blue level and 'Push' mode, for scenes where lighting conditions fall outside of the normal auto/preset range limits.

Performance

Resolution and low light sensitivity were both in line with the manufacturer's specs. In good natural light the image looks clean, sharp and detailed with no significant picture noise. Noise increases as light levels fall but it is by no means excessive for a camera of this type.

On our sample colour balance, in natural light, was spot on, and whilst mixed natural and artificial lighting can result in a very slight colour caste it is far from serious, and the manual controls are only likely to be needed in really difficult situations.

When the scene is evenly lit the camera's auto exposure controls are reasonably effective and it reacts smoothly to gradual changes in light level. However, as previously mentioned, it is not without its foibles. Under some conditions, particularly where there is a marked contrast between the lightest and darkest parts of the scene, the exposure system appears indecisive and can start to 'hunt', causing the image to pulsate.

Re-positioning the camera, switching to shutter control and experimenting with iris and backlight settings can all help, but clearly this could be inconvenient once the camera is in place, particularly if it is in an inaccessible location.

On a more positive note, mechanical stability is excellent and the video output remained rock-steady when the camera was subjected to a few good taps with the trusty Security Installer rubber mallet.

What the manufacturer says ...

This versatile, installer-friendly unit combines a weatherproof housing, blower (heater optional), adjustable sun shade and dual power (12VDC/24VAC). It is a robust, all-purpose outdoor camera which can be used in demanding locations.

Utilizing a 1/3" high resolution Color DSP Sony Super HAD CCD, the camera features a basic day/night function for a cleaner low-light picture (not IR sensitive). The 5-50mm DC auto-iris lens is suitable for varied usage. The camera is covered by a 1-year warranty. It has signal to noise ratio of more than 48dB, while gamma correction is r = 0.45. The camera weighs 2.8lbs (1.25kg) and colour is ivory. Video output is 1Vp-p, 75 ohm.

The camera offers 480 lines of crisp resolution and 0.5 lux minimum illumination. Plug and play is an over-used phrase, but this unit could not be more simple to install. It is ideal for car park surveillance, entrance and exit security and usage in any harsh outdoor environment.