What is the difference between auto iris and direct drive lenses?

• An Auto Iris lens adjusts its iris automatically in response to changes in scene illumination levels. An amplifier drives the motor that opens and shuts the iris by processing a little electronic signal that changes with the light level.
• This Amplifier is not present in a Direct Drive 'DD' lens, and it can only be used with a camera that has one.
• The possible output options will be listed in a camera's datasheet.
• Because the driving amplifier is in the camera, the smallest auto-iris lenses have few circuitry within. These 'direct drive' (DD) lenses feature a built-in cable that connects to the camera and usually has a square 4-pin connector port.

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