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Selecting the right lens for your camera an mean a world of difference, most professional installation are configured camera-by-camera using a focal point distance chart (see the bottom of this page).
There are 2 things you should consider when selecting a lens for your camera:
1. Focal Point Distance (see chart below), The focal length of the lens is measured in mm and directly relates to the angle of view that will be achieved. Short focal lengths provide wide angles of view and long focal lengths become telephoto, with narrow angles of view. A "normal" angle of view is similar to what we see with our own eye, and has a relative focal length equal to the pick up device. Our online lens calculator is a simple to use device for estimating focal length, object dimension, and angles of view.
2. Automatic or Manual IRIS, Generally we tend to use auto iris lenses externally where there are extreeme variations in the lighting levels. Manual iris lenses are used normally for internal applications where the light level remains consistant. When using an auto iris lenses it is necessary to control the operation of the iris to maintain perfect picture levels. Video driven lenses contain amplifier circuitry to convert the video signal from the camera into iris motor control. With direct drive lenses, the camera must contain the amplifier circuitry, and the lens now only contains the galvanometric iris motor making it less expensive. The deciding factor depends on the auto iris output of the camera. Most cameras now have both types.
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