Bosch Special (FAQ: Practical Tips For Security Lighting) En US 1212683659

User Manual: Bosch Special (FAQ: Practical Tips for Security Lighting) NEI-30 Dinion IP Infrared Imager

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CCTV Illumination

Practical Tips for Security Lighting

4 | Practical Tips for Lighting

The overall effectiveness of any integrated surveillance

system depends on its ability to deliver useful images at

night.

Specifying and installing the correct type of illumination

for night-time surveillance is easy if you plan properly and

follow a few simple rules. Here, Bosch Security Systems

presents practical tips and advice to ensure you get the

best performance from its range of high performance LED

infrared illuminators and visible White Light

1. Specify the correct type of light

Choosing the right lighting for each individual

application is critical – here are some things to consider

Infrared or White Light?

This depends very much on the purpose of the system.

Infrared light enables cameras to deliver useable images

at night. 850nm IR enables long-range surveillance

capabilities, and has a discreet but visible glow which

can draw attention to the camera and deter any criminal

that infrared, by cutting down on image noise, can

significantly reduce network storage requirements may

come as a welcome surprise.

Low light levels increase the bit rate of encoded video

streams and if left unaddressed will result in greater

storage needs. Installing IR illumination enables cameras

to deliver high quality night-time images with virtually

zero noise. Reduced noise allows for better

compression, reduced bit rate, better use of bandwidth,

lower storage requirements and all the associated cost

savings.

8. To avoid light pollution, use infrared illumination

rather than visible light for security.

This leaves the night-time environment unchanged for

people and animals. If deterrent or safety lighting is

required in combination with security, a visible White

Light LED solution like Bosch’s AEGIS SuperLED White

Light unit is best. Both LED infrared and White Light

illuminators deliver far better energy efficiency than bulb

based products and as such can deliver huge savings in

terms of running costs and CO2 emissions.

9. Specifying the correct illuminator is important so as

not to waste light in areas of the scene that the camera

is not viewing.

This in turn leads to increased operational costs and

lower performance, especially if the illumination angle is

wider than the field of view or worse still, if the

illumination angle is less than the cameras field of view.

This will result in a very bright, over-exposed spot in the

centre of the screen and black halo surrounding it.

Specification is easy if you have a lens wheel or can

perform some simple trigonometry, alternatively you can

use our HTML based web tool to select the right

illuminator for the job.

10. When using infrared illumination, always use an

infrared corrected lens or zero-focus shift lens.

As infrared illumination is further from the central part

of the visible spectrum, most standard lenses have not

been designed to cope with this wider range.

IR-corrected lenses have a coating applied to the optic

to allow both the colour and infrared wavelengths to be

focused correctly on the sensor. This coating is also

anti-reflective in the near infrared range, which increases

the throughput of infrared through the lens and onto the

sensor.

INCORRECT

Illuminator mounting height

lower than 3 metres

< 3 metres

CORRECT

Illuminator mounting height

greater than 3 metres

INCORRECT

Illuminator mounted

above camera

CORRECT

Illuminator mounted

below camera

> 3 metres

INCORRECT

Illuminator mounting height

lower than 3 metres

< 3 metres

CORRECT

Illuminator mounting height

greater than 3 metres

INCORRECT

Illuminator mounted

above camera

CORRECT

Illuminator mounted

below camera

> 3 metres

2 | Practical Tips for Lighting Practical Tips for Lighting |

3

activity. 940nm IR has no visible glow so is perfect for

covert surveillance, however it does require a very IR

sensitive camera to work to its optimum capabilities.

Quick start, LED White Light can be used to illuminate

an area safely for pedestrians, staff and vehicles, and

can also be used as a visual deterrent when an intruder

is detected by a PIR.

Angle and Distance

The illumination should ideally match the angle of the

camera and lens in order to deliver optimum

performance. After selecting the angle, the next

consideration is distance. How far should the lighting

illuminate considering that as the angle increases,

achievable distance will decrease?

Camera and Lens

Exact performance of any illuminator depends upon the

camera and lens combination used. For best results, a

high sensitivity camera (for IR projects an IR sensitive

camera) should be used with a high transmission lens

2. Mount the illuminator at a height of greater than

three meters.

Mounting any illuminator at this height will greatly

reduce the intensity of the light directed into the

foreground and prevents objects at the front of the

scene becoming overexposed. Innovative 3D diffuser

technology used in Bosch’s AEGIS illuminators negates

this problem by distributing light to the foreground and

background of the scene enabling perfectly evenly

illuminated CCTV images. (figure 1)

3. When mounting an illuminator with a camera

housing or AutoDome style camera, the illuminator

should be mounted underneath the camera.

The illuminator should be at least 300mm from the

camera. Insects and spiders are attracted to the heat

generated by the illuminator and can interfere with video

content analysis and motion detection software. Spiders

tend to nest near sources of heat, and although this will

have little impact on the illumination output, nobody

really wants a spider calling their camera lens home.

(figure 2) Also if the illuminator is mounted above the

camera housing, a shadow will be cast (in the same way

as sunlight behind a building) compromising

surveillance.

4. Synchronize your camera and illuminator using the

IO ports on both components.

There are two ways to do this, either with the camera

leading or the illuminator leading.

When it comes to camera leading, the decision to switch

is based on video level. The advantage is that it gives

you greater flexibility (all cameras are different and this

allows for the camera to be set to the user’s preference)

The disadvantage is that when the illumination is

switched on, the camera will switch to monochrome and

the image noise level will increase significantly. Although

cameras have built in lag to avoid this, at times the

illumination can overpower this safe guard.

Illuminator leading is a decision based upon the light

level. The advantage is that when the illuminator comes

on, the camera moves to monochrome based upon the

absolute light level. Assuming this has been set

accurately, the camera will produce low noise images

and will not switch too early. The disadvantage is that

the light level at the photocell is not necessarily the

same as that on scene.

5. Illumination aids megapixel and HD imaging

Megapixel cameras have similar sensor sizes (active

area) to capture photons as standard definition cameras,

but this area is divided up into far smaller ‘buckets’

know as pixels. Dividing the total illumination between

more pixels means that each pixel gets proportionally

less light. This generates a lower quality video signal if

the gain function of the camera or the number of

photons that hit the sensor are not increased. Therefore,

the trade-off for increasing resolution is generally

reduced low-light performance.

More pixels equal more components, especially for

CMOS sensors, which generate additional heat into the

active area of the sensor. This leads to an increase in

the noise of the image produced in both daylight and

night-time conditions. To enable high clarity imaging in

low light two megapixel cameras would appear to

provide the best resolution and sensitivity balance.

6. When using 1/4" sensors like those found in fully

functional pan-tilt-zoom cameras, the same idea

applies.

The pixel count often remains the same as for 1/3" and

1/2" sensors but obviously the total active area

decreases. Think of a mobile phone camera; if you try to

use a phone camera in the dark the images produced are

disappointing. Ensure you have enough, and the right

type of illumination for any critical surveillance

applications.

7. Use infrared to improve bandwidth management

Given that storage is one of the biggest expenses

incurred when operating a surveillance system the fact

Figure 1

Illuminator

mounting

height

Figure 2

Illuminator

mounting

position

Bosch’s AEGIS

LED infrared and

white light

illuminators

deliver reliable

performance, low

maintenance and

running costs

and enable

night-time

imaging at

distances of up

to (320m /

1050ft)