Canon Patents

Patent: Improved EF to EF-M Adaptor

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A new patent for an EF to EF-M adaptor has appeared. It looks like the new adaptor will have improved AF speed with EF lenses mounted. As many of you know, the current adaptor is pretty sluggish in that regard.

The patent makes a point of saying there will be improved performance for video and liveview. Could the video improvement be for dual pixel AF? Could this patent be related to the GH4 competitor we’ve been told would launch at NAB?

The patent details are after the break….

Patent Publication No. 2015-34903

  • Published 2015.2.19
  • Filing date 2013.8.9

Master lens

  • Zoom ratio 2.69
  • Focal length 72.13 135.02 193.99mm
  • Fno. 2.90
  • Half angle ω = 10.72 5.78 4.03 °
  • Image height Y = 13.66mm
  • Overall length of the lens 237.36mm
  • BF 54.00mm

Adapter installed

  • Zoom ratio 2.69
  • The focal length f = 72.12 135.00 193.96mm
  • Fno. 2.90
  • Half angle ω = 10.72 5.78 4.03 °
  • Image height Y = 13.66mm
  • Overall length of the lens 239.70mm
  • BF 16.77mm

Canon patent

  • Fast AF adapter
  • Wobbling corresponding
  • 3-group configuration of positive and negative positive
  • 2 group also serves as a focus group and the anti-vibration group
  • And realize high-speed AF focus group was lighter

Source: [Egami]

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