Lens selection is especially critical since the choice directly affects the size, and quality of the image. Various options are available to meet the most demanding of requirements.

There are 3 main types of lenses: manual, auto iris and direct drive (DC iris).


This type of lens has an iris which is manually adjustable by hand and can only be used in areas where the light level is fairly good and constant and there is little effect from changing light levels e.g. sunlight through windows.


This type of lens is needed when using cameras outdoors or in areas where the light level is changing or where affected by external sources e.g. sunlight. The lens contains an amplifier which converts the video signal from the camera into a voltage that drives the iris motors on the lens to open or close.

Direct Drive:

These lenses work in much the same way as auto iris lenses but they do not contain an amplifier. These lenses utilise amplifiers that are built into the camera on which it is to be used. This tends to make them slightly cheaper than auto iris lenses.