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Technical support > Support selection > Manufacturer Tech Tips
Choosing the correct lens
Choosing the correct lens can be one of the most important decisions for your installation. Here are a few simple guidelines.
- It depends on camera position and the view required. The wider the field of view, the less detail will be available and vice versa.
- The easiest way to choose is to use a view finder, which, when held to the eye, will indicate the view to expect on the monitor.
- If a view finder is not available, a lens calculator, or lens calculator software, will make the job easier. The only other alternative is to resort to measuring angles, and comparing them to lens specification sheets.
AUTO IRIS or MANUAL IRIS
Manual iris lenses are usually chosen for use internally when the light level remains the same, thereby avoiding the need to adjust the iris to changing light levels. Cameras with electronic iris can adjust the picture in the camera to compensate for changing light levels.
It is preferable to use Auto Iris lenses for external applications where light levels can change considerably during a day as an auto iris lens automatically changes the iris to suit the light level.
Once you have chosen an auto iris lens - do you use video drive or direct drive?
Standard auto iris lenses are video driven which means the lens itself contains the amplifier to convert the video signal from the camera into the control for the iris motor. Direct drive lenses are cheaper as they only contain the motor drive for the iris, therefore the camera must contain the amplifier.
Most cameras listed on this web site may be used with either auto iris or direct drive lenses.
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