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Choosing an Axis T90B illuminator

The Axis T90B illuminators are a versatile series that include both infrared and white LED models for enhanced low-light surveillance. Selection of Axis illuminators

They share many features but there are different advantages to using either infrared or white light. We overview the features and highlight the options on offer to help you choose which model is the best fit for your surveillance needs.

Features overview

All units are housed in durable IP66 and NEMA 4x-rated casings, making them suitable for both indoor and outdoor use and a range of mounting brackets is also available for easy installation (sold separately).

A narrow 10° default lens is included with each illuminator as well as a choice of additional diverging lenses that offer wider beam angles to match your chosen field of view. Axis have used holographic lens optics here for accurate and even illumination to help prevent hotspots and the loss of detail through overexposure. Each unit can also be configured to turn on and off via the integrated photocell or via a connected camera’s I/O port (camera model dependent) or PIR sensor.

An optional remote control is available, allowing the user to optimise illumination settings from the ground – very helpful!

All in all, a great set of features but do you opt for an infrared or white light model?

IR or white LEDs?

With the exception of thermal cameras, most IP cameras need a certain level of lighting to produce an effective image in very low light. The choice between using IR or white LEDs to produce that lighting will depend on a variety of factors including:

  1. the features and capability of your camera(s)
  2. the distance to be lit
  3. if the overt use of illumination will act as a visual deterrent
  4. whether you need to detect, identify or recognise people or objects in the scene and if the use of full colour will aid that

The comparison table below highlights these factors and illustrates which requirements are met by using infrared or white light.

Requirement IR White LED
More effective surveillance in low light or complete darkness
Storage and bandwidth optimisation through the reduction of image noise
Discreet surveillance – minimising awareness of illumination  
Illumination where the use of artificial light is unsuitable  
Lighting narrow fields of view at distances of 150 metres or more  
Visual deterrent – maximising awareness of illumination  
Monitoring in full colour to aid detection, recognition or identification  
Boosting light levels to assist camera technology such as Axis’ Lightfinder  
For use with IP cameras that do not have a built-in IR cut filter  

Angles of illumination

Once you’ve decided whether it’s IR or white light that best meets your requirements, you then need to consider the angle of illumination and distance that needs to be covered. It is important to match the angle of illumination to the camera’s field of view. A narrow beam of light on a wide scene can produce a bright spot on the image and wide angle illumination on a narrow scene results in light wastage and reduced performance.

Each of the Axis T90B illuminators is supplied with diverging lenses to change the default 10° beam angle to either 35°, 60° or 80° (these angles are even wider when lenses are paired on the twin T90B40 model). A 120° lens is also available separately for use with all models to cover very wide scenes.

The two graphics below illustrate the difference between the distances and illumination angles that can be covered by each unit in the range.

Axis T90B IR LED illuminators
Illustration of Axis IR illuminator beam angles
Note, the AXIS T90B40 IR-LED comprises two LEDs. Depending on the required angle of illumination (narrow or wide), the T90B40 reaches different distances.

Axis T90B white LED illuminators
Illustration of Axis white light illuminator beam angles
Overall, the white light units are lower powered and don’t cover the longer distances that their IR counterparts are capable of but they’re still very effective.

Summary

Using professional lighting with IP cameras helps to reduce noise in images and provide higher quality pictures. Compression techniques are also able to work more effectively when image noise is reduced and this substantially reduces bandwidth and storage requirements.

The Axis T90B illuminator range offers flexible lighting solutions to enhance the low-light performance of your surveillance system. If you’re still unsure which model to choose or need further advice on the use of illumination with your IP CCTV system, just get in touch and we’ll do our best to help.

Published on April 14th, 2016 by Network Webcams

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