A Lens Controller is device that controls motorized photographic lens

Photographic lens

A camera lens is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.While in principle a simple convex lens will suffice, in...

 functions such as zoom

Zoom lens

A zoom lens is a mechanical assembly of lens elements for which the focal length can be varied, as opposed to a fixed focal length lens...

, focus

Focus (optics)

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...

, and iris

Iris (diaphragm)

An iris is a mechanism that is used as a compact solution to close and open holes. It is made up of usually a series of metal plates that can fold in on each other or expand out. Iris mechanisms are commonly found in optical shutters , and also in various kinds of valves. Irises are sometimes used...

 or aperture. Lens controllers can be found internally in modern still camera photographic lens

Photographic lens

A camera lens is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.While in principle a simple convex lens will suffice, in...

es and as a stand alone unit in machine vision

Machine vision

Machine vision is the process of applying a range of technologies and methods to provide imaging-based automatic inspection, process control and robot guidance in industrial applications. While the scope of MV is broad and a comprehensive definition is difficult to distil, a "generally accepted...

, remote sensing

Remote sensing

Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...

, optoelectronics

Optoelectronics

Optoelectronics is the study and application of electronic devices that source, detect and control light, usually considered a sub-field of photonics. In this context, light often includes invisible forms of radiation such as gamma rays, X-rays, ultraviolet and infrared, in addition to visible light...

 systems, and security applications.

Internal Photographic Lens Controllers

Internal lens controllers take information from the camera or lens elements and perform automatic and manual focusing and aperture adjustment. They are frequently contained inside as part of a modern zoom lens and used mainly for photography.

Stand Alone Photographic Lens Controllers

Stand alone lens controllers are attached to a photographic lens by a cable to allow operator manual control of lens functions.

Machine Vision, CCTV, or Computer Vision Lens Controllers

Lens controllers for machine vision are universal devices designed to control lenses from multiple manufacturers. Although there is no standard for wiring of lenses most have Direct Current (DC) motors attached to lens elements and are controlled with +-6 VDC, +-8 VDC or +-12 VDC.

Machine vision lens controllers come in manual or computerized varieties.

Manual lens controllers are composed of switches and a power supply. When the operator actuates a switch

Switch

In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another....

, a function of the lens is enabled. Manual control requires an operator to view the image through the lens in which adjustment is taking place. Manual lens controllers are the most common and are frequently used in CCTV security systems.

Computerized lens controllers are composed of a computer, electronic switches such as H-Bridge

H-bridge

An H bridge is an electronic circuit that enables a voltage to be applied across a load in either direction. These circuits are often used in robotics and other applications to allow DC motors to run forwards and backwards...

s or relay

Relay

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...

s, a power supply, and an electronic interface. A remote computer sends a command to the lens controller through an RS232, RS485, USB, or Ethernet

Ethernet

Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....

 interface to actuate a lens function. The Lens Controller will then perform the command automatically. If a lens is equipped with presets, potentiometers attached to lens components that measure the position of that function, then the controller can work in a closed loop

Closed loop

Closed loop may refer to:* A feedback loop, often found in:** Control theory#Closed-loop transfer function, where a closed-loop controller may be used** Electronic feedback loops in electronic circuits** PID controller, a commonly used closed-loop controller...

and move to a specific position. If the lens is not equipped with presets, then the controller can only move a lens function to an approximate position.