The bench test 2: Throwing some light on the subject

What our experts say …

The specifications and feature lists for most video surveillance devices tend to be couched in a fairly matter of fact way, but whoever was responsible for the manual accompanying the new Samsung Techwin SCH-721A colour video day/night camera clearly moonlights as a food or wine writer, judging by the surfeit of flowery techno jargon and TLAs (three-letter acronyms).

We’ll start with some easy ones. The 721A is billed as a WDR model with a SV-II DSP chip. This translates as ‘wide dynamic range’ with digital signal processing, which basically means it delivers a crisp sharp picture in a wide range of conditions. For good measure there’s also an ‘assistant’ SSNR (Samsung Super Noise Reduction) chip for removing picture noise in low light.

The image sensor chip comes in for some special treatment. It’s made by Sony and it’s a 1/3-inch ‘vertical double density interline’ CCD with an array of 752 x 582 ‘double speed’ pixels. This gives it a claimed resolution of 500 lines in colour/day mode and 550 lines in night mode. Minimum illumination in colour mode is a very respectable 0.3 lux, and this falls to just 0.01 lux when it switches to night mode and the IR cut filter slides back from in front of the sensor.

Enough already. Suffice it to say the 721A

is a well-appointed multi-role camera with some handy extras, like a motion detection system that can trigger an external alarm. There’s also a useful set of exposure options, including backlight control and electronic shutter, auto/manual white balance, gain and sensitivity controls, four privacy masks, a moveable one line/16 character camera title, and a facility for external remote control/setup.

It’s a snazzy looking design with two-tone grey and cream casework. The lens mount accepts C and CS type lenses (an adaptor ring is supplied) and there’s a simple back focus setting that uses one of the smallest Allen keys we’ve ever seen to lock the adjusting ring. It’s thinner than a paperclip and destined to get lost, so take very good care of it!

On the left side of the camera body is a standard four-pin socket for an auto-iris lens (DC or video controlled), and next to that is a sliding panel that opens to reveal a set of five buttons for accessing and controlling the on-screen display.

On the rear panel there’s a BNC socket for the video output, a pair of screw terminals for the 12v DC/24v AC supply (a mains powered version is also available), a four-pin socket for the external remote control, and four spring terminals for the motion detector alarm output connections. In the middle there’s a green power-on LED and below that an earthing screw.

Inside the camera the main PCB, daughter boards and power supply modules are bolted to a tough-looking steel chassis. The image sensor module connects to the main PCB by a short ribbon cable; otherwise interconnections are kept to an absolute minimum.

It’s very solidly built and looks like it should be able to withstand a fair amount of punishment. It’s not a weatherproof design, but the internals are well protected by the close-fitting steel outer shell and cast alloy front panel from the ingress of moisture and airborne contaminants.

Setup and operation

Pressing the centre button on the hidden control panel brings up the on-screen display, which has ten options. From the top, the first five are for the Camera ID (on/off and title compose), Backlight control (BLC or WDR), White Balance (wide auto tracking 2400-12000k, special auto tracking 1800-6000k for sodium lighting, auto and manual) and Motion Detection.

Motion Detection has two operating modes: MD1 responds to motion by monitoring changes in outline or colour change, and MD2 reacts to changes in brightness.

In MD1 the size of the detection area, which occupies the centre portion of the screen, can be adjusted using the cursor buttons. The MD2 mode divides the whole screen up into 48 ‘targets’, which can be individually switched on or off. In both cases sensitivity levels are set using a simple on-screen ‘slider’.

When motion is detected the alarm relay is activated and an on-screen message briefly appears with a counter that increments up to 999. The instructions seem to imply that the counter has to be manually reset at 999, adding a somewhat vague statement that “...when this feature is activated, another algorithm may take more time to be activated”.

We set up a simple test rig to try and find out what this means, but the counter on our sample went back to zero when it reached 999 and continued counting as normal. One of life’s little mysteries... The remaining five menu items cover Auto Iris lens selection (DC, Video or manual), Shutter (auto, manual 1/50 to 1/200,000th sec in 13 steps and off), Sensitivity (auto or manual), Gain (AGC high, AGC low, off) SSNR (high, middle, low or off) and Special.

This last menu includes switches for the day/night mode (colour, B/W auto), Sync (internal or external line lock) and the Privacy mask setup, which can be used to define up to four areas using a similar technique to the MD1 motion detector. This last sub menu also has a Reset switch to return the camera to its factory default settings.

Performance

Our test sample came within a whisker of the manufacturer’s resolution figure and it delivered a very clean and highly detailed image across a wide range of lighting conditions.

Low light sensitivity can be very good, but we found that some combinations of gain-up and sensitivity settings resulted in a flashing picture as the falling light level reached a particular threshold, so installers are advised to monitor the picture carefully under all possible lighting conditions.

Colour accuracy proved to be fairly average with some colours, especially reds, looking a touch over-saturated, and the auto white balance system had trouble coping with tube lighting but there’s plenty of scope for manual adjustment so it’s possible to achieve a reasonably natural-looking picture with a little tinkering.

The exposure system also needed a fair amount of manual intervention to handle difficult conditions and despite the backlight controls, bright lights within the scene area can still cause problems, so care needs to be taken when positioning the camera to avoid strong lights and windows.

As expected the 721A proved to be very stable, and the picture remained rock-solid whilst subjected to a good beating with the Bench Test rubber mallet.

What the manufacturer says ...

The SHC-721A Wide Dynamic Range Day/Night colour camera incorporates Samsung Techwin’s unique Super Noise Reduction (SSNR) technology.

When lighting levels are low, SSNR dramatically reduces both random and fixed noise and at the same time produces a high signal to noise ratio and no ghost effect.

In simple terms, the result is clear sharp images, even in the most severe lighting conditions.

The absence of any “ghost” affect, which is normally quite common in low light conditions, offers a higher level of identification – a big plus where, for example, there is a requirement to recognise number plates.

An additional benefit of this technology is the reduced file size of recorded images. A DVR’s recorded file size is reduced by a massive 70% when using a MPEG format and by 40% when using a JPEG format.

The SHC-721A WDR camera has an integral ICR (Infrared Cut Filter) which ensures best possible colour images during the day, but maximises sensitivity to infra-red at night in monochrome mode.

The normal sensitivity of the camera allows images at an illumination of 0.2 lux (AGC on) with a F1.2 lens, and as low as 0.003 lux in Sense-Up mode.

Samsung Techwin’s Dual Automatic White Balance technology ensures a true colour image without tending towards red or blue.

Built-in motion detection provides for the camera view to be divided into 48 detection zones, and the sensitivity level is set and adjusted via the on-screen display.

The SHC-721A also incorporates Samsung Techwin’s SuperVision II superior back light compensation, which creates two fields of each image. These are analysed and then combined into one composite picture. The result is ultra sharp clear images.