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CCTV and IP Video Guide, Tips & Tricks

In the near future we plan to enhance this section by adding informative articles about the following topics:

  • Tips & tricks
  • CCTV lenses
  • Compression
  • IP video design practices
  • Networking principles
  • Video storage

For readers who are not very familiar and comfortable with terms used in conjunction with our products and service, we have a IP video and CCTV glossary where you can find explanation of widely used words, like  focal length of a lens, camera format, auto iris,  H.264,  field of view calculation, wide angle lens, cctv compression, network bandwidth and cctv storage calculation and more.

Apart from providing rich source of information within our website, we have also provided external links below to some of the most interesting  CCTV design resources:

  1. There is a document called “CCTV Operational Requirements Manual” from UK Home Office Scientific Development Branch. This manual helps to understand the concept of recognition, detection and identification used in IP Video System Design Tool.
  2. There is a very interesting and useful video from FBI. This video explains how to avoid common CCTV design problems such as using wrong camera lenses, installing cameras in the wrong locations, using low FPS and wrong compression and much more.

Bob Dolph (Security Sales and Integration) has written an article about this video.

Here is a preliminary version of a video tutorial on how to add a site plan to IP Video System Design Tool, find optimal camera locations, calculate camera lenses and required camera resolution.

Wide Angle Lenses

Wide angle lenses have many advantages for CCTV and IP video surveillance. The first advantage is wide field of view (See images bellow). The second advantage is  good low-light performance. And last but not least, wide angle lenses provide good depth of field as compared to telephoto lenses. However these advantages do come with a few drawbacks as well such as the possible geometrical distortion which appears as visible curvatures at the edges of a camera image and higher requirements for the camera resolution.

Hence it is important to maintain a proper balance between the wide field of view and possible drawbacks of wide angle lenses.

To find a proper focal length for wide angle lens, the CCTV designer needs to perform many calculations. To ease the lens selection the designer can use special 3D CCTV design software where you can clearly see all 3 parameters: actual field of view, lens distortions and camera resolution.

wide angle lens distortion example Wide angle lens

Focal length of a lens. Focal length calculator

focal length of a lens

When rays of light pass through a convex lens (the shape of lens shown in figure above) they tend to converge at a single point at some distance ahead of the lens. This distance between the lens and the point where they focus is known as the focal length as specified by the symbol f in the figure. In case of a CCTV camera, the lens focuses the rays at a point where the sensor is placed.
The combination of the focal length of the lens and the size of the sensor determine the field of view of the CCTV camera. The shorter the focal length, the wider the field of view, and vice versa.

In the earlier days,  rotating focal length calculators made out of paper were good and simple tools for quick calculation of the field of view.

However these days, we have much more sophisticated tools and techniques such as  CCTV CAD /CAE software for CCTV design, like CCTV Design Tool or IP Video System Design Tool.

focal length calculator

Apart from the focal length calculator this software has 3D engine for automatic design and visualization of all elements of video surveillance systems.

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