Skip to content

[Patent] Canon Patent For Improved Phase Detection Auto Focus

Phase Detection AF

Egami (machine translated) found a patent by Canon regarding an improved Phase Detection Auto Focus. Such a “hybrid” autofocusing system has been featured on the Rebel T4i/650D and the recently announced EOS M. The patented technology aims at improving speed and accuracy. Is this the AF system that Canon will implement on its next, more pro-oriented mirrorless camera, expected to be announced later this year?

  • Patent Publication No. 2010-60771
    • 2010.3.18 Release Date
    • 2008.9.3 filing date
  • Existing techniques
    • Patent Publication No. H11-281878
    • Different lengths of baseline using the AF sensor
      • F2.8 sensor: high focusing accuracy
      • Can detect a wide range of defocus amount (the amount of deviation of focus): F5.6 sensor
      • After roughly at F5.6 sensor is focused, making focus F2.8 sensor with high accuracy
    • Drawback
      • Depending on the timing F2.8 sensor is not used, focusing accuracy is not good
  • Canon’s patent
    • Different lengths of baseline using the AF sensor
      • Because of the defocus amount detection range is limited, must search as duplicate detection range
      • By using the F5.6 sensor, within a limit not exceeding the amount of defocus, it is possible to focus lens is driven at high speed
    • If the Live View
      • The image plane using phase difference AF
      • Focus lens is driven at high speed
        • Using the central pixel: When low-intensity
        • Using the neighboring pixels: When high-intensity
Imaging surface phase detection AF
[via Egami]
Back To Top


This website or its third-party tools use cookies, which are necessary to its functioning and required to achieve the purposes illustrated in the cookie policy. If you want to know more or withdraw your consent to all or some of the cookies, please refer to the cookie policy.
By closing this banner you agree to the use of cookies.