Auto-focus/Automatic camera: An example of mechatronics system




In a modern camera using film, we can see automatic focusing and exposure facilities. The basic elements of the control system used in an automatic camera are body, lenses, and flash. Figure 1 depicts an automatic camera system.

Figure 1: Components of an automatic camera


Figure 2. Key components of an automatic camera and its block representation

  • Depending upon the model selected, the required combination of aperture and shutter speed and focus are automatically taken care of by the camera. 
  • A typical camera system comprises drives and sensors, interfaces for lenses, flash, and user. 
  • Drives are required for film advance, rewind, shutter movement, focusing, zoom, etc. 
  • The sensors are essentially used for sensing film speed, counters, focus, exposure, zoom, etc.
  • Microprocessor systems for lenses, a user(s), and flash are incorporated for controlling various operations.
Figure 3 Working of autofocus system of automatic camera

  • The user is expected to feed information for achieving the desired composition. 
  • When the switch is ON, it activates the system and the object is photographed. The microprocessor takes the input from the range sensor and sends the output to the lens. The lens position is fed back to the microprocessor and it modifies the same. The light sensor gives an input to the microprocessor, and the microprocessor gives an output to be determined. 
  • When the photographer selects the shutter controller, the shutter opens up for the photograph and the photograph is taken, the microprocessor gives an output to the motor drive to advance the film for the next photograph

Figure 4: Inside camera before and after the shutter button is pressed (acquiring image)

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