Cameras, just like people, need light to see at night. So every security professional will benefit from a core understanding of light.

Despite the importance of lighting, it is sometimes overlooked or specified incorrectly when it comes to the design and installation of a security system; often due to a lack of understanding. Raytec are 100% focussed on lighting and six of Raytec’s lighting experts who each have over 10 year’s personal experience of lighting design (and collectively over 100 years) reveal their personal tips and practical guidelines for making lighting design, specification, installation and set-up much easier and more effective. This article will help all security professionals to understand the basic principles of light and get the most out of their security system at night.

Tips from 100 Years in Light

This paper will cover the following topics:
• Optimal lighting and camera integration
• The importance of real life testing
• Identifying new opportunities with White-Light
• White-Light design and specification
• The impact of badly designed lighting
• The true cost of ownership of your lighting

Optimal Lighting and Camera Integration

Pro-Tip “Don’t look into the light!” David Lambert, Sales and Marketing Director

Camera alignment and set-up is crucial for achieving the best CCTV images at night and the highest level of security. Cameras, just like human beings, rely on light reflected from objects in the scene to produce an image, so it is crucial to correctly position your lighting to fully illuminate your chosen scene and match the angle of illumination to your camera fi eld of view.

Consider Figure 1. If your illumination is positioned so that it looks into the camera lens (or a human’s eyes), not only will it produce glare, but it will result in a scene that is not properly illuminated and an image with white-out or over exposure.

Figure 2 shows a scene which is correctly illuminated with the lighting positioned alongside the camera looking out onto the scene and using the correct output angle for the scene requirements. With the correct alignment and set-up, users can achieve even illumination across the entire scene, with excellent clarity, no dark spots or over exposure, for the best images at night

The optimal position for your illuminator is adjacent to the camera and pointing out and down towards the scene. Take care when locating your illuminator near a dome camera – we generally advise at least a 1 metre separation to avoid the possibility of light entering the dome and creating unwanted reflections.

The distribution of light and the amount of light govern the quality of night-time CCTV images. For this reason it is critical to match the angle of illumination to the camera field of view to achieve the correct distribution (spread of light) and full coverage for your specific scene.

Distribution of Light

The correct illumination angle for a specific scene requirement could range anywhere from 5° for ultra long distance applications, right up to full 360° coverage for dome camera applications. A narrow beam of light on a wide camera field of view can produce a bright spot or over exposure on the image and wide angle illumination on a narrow scene results in light wastage and reduced performance. The examples below clearly illustrate the advantage of matching the angle of the illumination to the field of view of
the camera.

Lighting solutions that provide the ability to alter the angle of the illumination will always be able to provide the best possible solutions and Raytec have developed a number of solutions to provide maximum flexibility:

• Raytec’s Adaptive Illumination™ can be used to quickly and easily alter the horizontal angle of illumination on site to match the camera field of view, anywhere from 10-180° (model dependant). The vertical angle of the illumination can also be altered by tilting the unit up or down to match the requirements of a particular scene.

• Raytec also offer lighting solutions with interchangeable lensing. This means that you can match the angle of illumination with the field of view of the camera at all times – slotting in a different angle lens if required.

1. Distance Calculator

Given the distance achieved by one illuminator,
designers can calculate how many illuminators are
required to achieve a different distance.
To work out simple distances such as x2 distance,
x3 distance it is simply a matter of squaring the
distance multiplier.
Practical Examples
To achieve double (x2) the distance = 4 x the original
power is required (22) (or 4 illuminators)
To achieve triple (x3) the distance = 9 x the original
power is required (32) (or 9 illuminators)

2. Power Calculator

To work out the distance of multiple illuminators,
simply find the square route of the number of required
illuminators then multiply that number by the achievable
distance of 1 illuminator.
Practical Example:
How far will 6x RM200-AI-10’s cover?
Square route of 6 is 2.45.
6 x RM200-AI-10’s will cover 2.45 times the distance of
1 x RM200-AI-10
2.45 x 300m (984ft) (the distance of 1 illuminator)
= 735m (2,411ft)

Quantity of Light

A basic understanding of the inverse square law will help ensure that you achieve better lighting design, and have enough illumination to achieve excellent night time CCTV images. But what is critical to understand is that, as you increase your distance, it’s not as simple as merely increasing your light by the same amount.

The Inverse Square Law

Light obeys the inverse square law, so to fully understand the way that light travels, and its impact on CCTV systems, an understanding of the inverse square law is required. The inverse square law in relation to lighting states that the intensity of a diverging light source is inversely proportional to the square of the distance from that source. As light travels away from a point source it spreads both vertically and horizontally and therefore intensity decreases – not as a linear function, but as a square function. This means that if light travels double the distance, there will not be ½ power intensity (which would be a linear law) but there will be a ¼ of the original power intensity (a square law).

There are two ways that lighting designers can use the inverse square law to help design a lighting system.

1. To calculate the number of illuminators required to illuminate a certain distance (Distance Ratio)
2. To calculate how far multiple lamps will illuminate (Power Ratio)

Sometimes, dedicated CCTV lighting may NOT be considered essential during the design of a scheme. Existing street lighting or ambient light from buildings or windows might be considered as adequate illumination for CCTV. Sometimes the user may make do with lighting that is not specified correctly for the scene and then compensate by using camera settings to boost the image quality. However, if you want to achieve good CCTV performance and high levels of security, there are several reasons to note why this approach is flawed.

Automatic Gain Control

Automatic Gain Control (AGC) allows low light levels to be enhanced within the camera. However, if you already have a poorly lit CCTV image which will most likely be ‘noisy’ and pixellated ( from a lack of correctly aligned and evenly distributed illumination) the AGC will not only amplify light levels but it will also amplify the noise. So whilst your image may be brighter, the level of detail and clarity will be significantly reduced.

With high levels of gain and a noisy image, there are additional disadvantages. One disadvantage is increased bandwidth and storage if you are using a network camera system. The noisy and constantly moving image creates a high level of data to be transmitted and also prevents video compression from working correctly. Video compression is an essential part of a megapixel camera’s operating mode because without it, a lot more video data has to be transmitted and stored. This is because most compression techniques are based on the principle of only sending the updated data – i.e. those parts of the image that have moved or changed. The problem is that even though the scene may be static, the compression software is tricked by the noise in a poorly-lit scene into thinking that the whole image is ‘moving’. So huge amounts of useless data is transmitted and stored.

Video analytics are also affected by a noisy and poorly lit scene. Not only will the video analytics system not be able to search for and identify subjects and objects on scene, due to the poor level of detail and clarity, but the noisy and constantly moving image may cause the motion detection system to raise false alarms.

If light levels on-scene are good enough from the use of appropriate CCTV lighting, then the amount of gain required should be minimal thus improving picture quality and reducing bandwidth and storage requirements. Video analytics systems required good quality images – day and night – to work effectively.

Shutter Speed

With insufficient lighting on scene, a known trick to improve light levels is to reduce the shutter speed of the camera to lengthen the exposure time so that the camera can capture the maximum amount of light per frame. This may brighten a static image, but for a dynamic and moving scene, the shutter speed will be too slow to capture movement in real time and motion blur will occur. However, with the right QUANTITY & QUALITY of targeted light on scene, cameras with good sensitivity to light are able to use faster shutter speed settings, allowing full frame rate operation, catching movement with no motion blur even in low light environments.

If the light is correctly aligned to the camera field of view and delivering an even spread of illumination, often as little as 2-3 lux of illumination is needed to produce high quality images at light.

The importance of real life testing – not all scenes and scenarios are the same

If you are considering utilising 940nm Infra-Red LED lighting for a covert CCTV application, then it is crucial to understand that it will have a significant effect on the overall performance of your security system in terms of achievable distances. 850nm is the industry standard Infra-Red wavelength to which the majority of cameras are most sensitive.

850nm IR units produce a distinct red glow. 940nm is an Infra-Red wavelength which is predominantly utilised for covert applications where a visible red glow from IR illumination is not acceptable – e.g. railway or military applications. With a 940nm IR unit, the human eye would only see an extremely faint red glow – if you were very close.

What is crucial to understand about 940nm Infra-Red lighting is that because cameras are significantly less sensitive at 940nm compared to 850nm, achievable distances with 940nm are significantly reduced – you can expect to achieve 40% less distance or more. At 940nm you need the most sensitive cameras to produce the best results.

It IS possible to achieve good distances and high quality images with fully covert lighting, but the careful selection of your camera and lens is crucial. Raytec have worked with a lot of camera technology partners over the years and we’d be happy to take a look at your chosen camera and calculate the impact on distance when using 940nm Infra-Red LED lighting.

Not only do cameras have to work harder to produce acceptable pictures at 940nm, lenses are also working towards the edge of the performance window. Transmission at 940nm will be lower and focus shift from daytime to night-time operation at 940nm is more pronounced.

Our clear advice is that, unless absolutely necessary for operational requirements – ie military, police or railways – 850nm will also provide better pictures, longer achievable distances and easier focussing than 940nm.

Infra-Red Only: Focussing & Alignment

It can be challenging to set up cameras and Infra-Red lighting during the day. Even if you set it up with an IR filter during the day, you won’t always get a true representation of the scene and how the images will look at night.

IR filters are designed to fit over the camera lens to cut out all other wavelengths of light except Infra-Red. They can be used during day time set-up to mimic a night-time scene, so that the camera can see where the Infra-Red light from the illuminator will fall on the scene without disturbance from other light forms. Installers often use this technique in an attempt to set-up their Infra-Red illuminators in the correct position and angle for the scene in hand – but this technique can cause problems and has limited success.

In our experience, there really is no substitute for getting out on scene AT NIGHT.

IR filters can cause additional transmission problems. The filter acts creates a barrier and prevents a proportion of the reflected light from the scene passing through the lens to the camera chip. It can reduce the available light by 25% – and hence reduce overall system performance.

White-Light: Alignment

There are less issues when setting up White-Light systems during the day with regards to focussing. However, the same alignment issues exist in bright light conditions – but because White-Light is visible, alignment issues are easier to overcome.

Pictures above highlight the issues with alignment and focusing when cameras are set-up during the day.
The picture on the left shows the lighting is misaligned and out of focus.

Raytec Solutions

The focusing issue can be improved by ensuring that sufficient light is provided so that the camera and lens are not working at the edge of their performance envelope. 850nm lighting will always cause less focus shift than 940nm. There are a wide range of IR corrected lenses available which can significantly help with focus shift.

Raytec are delighted to announce the development of a Dedicated Daytime Set-Up Tool (DST) which will help the installer ensure that their lighting is pointing in exactly the right direction – even when commissioned during the day. The DST will be available from Q2/2013.

Identifying New Opportunities with Light

Often lighting is left to electrical contractors who do not always have the knowledge and expertise when it comes to lighting for security and safety. But the position and performance of the lighting on site has a dramatic effect on not only camera performance but also public safety. For this reason, security professionals are urged not only to take responsibility for the cameras on site but the lighting too.

More and more frequently installers provide lighting for surveillance cameras but possibly miss the chance to provide exterior general site lighting. There are significant opportunities for security integrators to increase sales, especially given the fact that the facility manager responsible for general lighting is often the same person security integrators work with when designing and installing a CCTV system.

White-Light can obviously be used for a wide variety of purposes including a combined solution for both camera lighting and general area illumination. It provides good visibility and a safe, welcoming environment for onsite personnel and even-illumination with no dark spots, whilst also providing the same crystal clear, energy saving White-Light to deliver excellent CCTV images from the site surveillance system.

Hospital – Case Study

Raytec and a local installer had already installed Infra-Red LED lighting for B&W cameras around key surveillance points for a large UK hospital. Following this installation, they identified the opportunity to deliver further energy and cost savings by upgrading the hospital’s existing old style exterior site lighting to new high performance, low energy White-Light LED. RAYLUX White-Light illumination replaced metal halide lighting in the car park and RAYLUX Urban lighting replaced sodium lighting on pathways, delivering improved safety and visibility, long life, reliability and significant energy and maintenance cost savings. The accurate colour rendition of the new White-Light LED units also allows the site colour camera system to achieve better surveillance images during the hours of darkness.

Following the installation, the hospital is making 70% power savings, has reduced their CO2 emissions by 40 tonnes of per year, and are set to save £80,000 on running costs and maintenance over the ten year minimum life of the installation.

Installers can utilise Raytec’s full support and expertise when pursuing lighting projects. Whether you are using Infra-Red or White-Light, Raytec’s team of expert lighting designers can help you design and specify the best lighting for your project requirements, for the highest level of night time surveillance and site safety, and energy and cost efficiency.

Raytec Lighting Design Service

Working closely with the customer, Raytec will firstly determine the purpose of the lighting for the specific application – whether that will be long distance CCTV lighting along a perimeter or wide angle dome camera lighting, lighting for safety within a car park, industrial lighting for a manufacturing facility perhaps, or an entirely bespoke application.

With the original site drawings from the customer, or even using satellite images, Raytec use lighting design software to create tailored lighting solutions to highlight the best lighting positions, minimum number of fittings and detailed lighting levels to meet the specific requirements of each project.

All Raytec White-Light products are photometrically tested by an independent laboratory to determine the exact power and light distribution of each unit. Using this photometric data in conjunction with lighting design software, Raytec lighting designers are able to provide a lighting solution which adheres to any specific lighting requirements. These can include details of whether the lighting is on a horizontal plane (lighting down onto a scene for general area lighting) or a vertical plane (lighting out across a scene for CCTV lighting), specific lux levels and uniformity requirements as well as other important performance characteristics.

Raytec can provide both 2D and 3D lighting designs.

2D Lighting Design Process

A 2D design is used to plot the individual light fittings onto the site plan, indicate the direction and spread of the illumination, and use contour lines to show detailed lux levels within different areas. This type of design explains exactly how Raytec will achieve the desired outcome, and can be used as a guide during the installation stage.