Canon Patent For 1.4x Extender (Updated)

I made a big mistake reading the patent. Thanks to DicaHub I can correct it. The patent is not for a 400mm lens with built-in extender, but for a 1.4x extender for lenses that do not support contrast AF. With such lenses a “wobbling” effect can appear when shooting video. The patent refers to an extender with movable elements to suppress the “wobbling” effect.

Egami (translated) spotted another patent filed by Canon, this time for a 400mm lens with built-in 1.4x extender.

• Patent Publication No. 2014-115410
  • Publication date 2014.6.26
  • Filing date 2012.12.7
• Master lens
  • Focal length f = 390.09mm
  • Fno. 2.90
  • Half angle ω = 2.01 °
  • Image height Y = 13.66mm
  • The overall length of the lens 367.66mm
  • BF 44.00mm
  • 15 pieces of 11-group lens configuration
  • Two fluorite
• Example 1
  • Focal length f =-226.69mm
  • 1.41x magnification
  • Five 4-group lens configuration
  • One piece of one sided aspherical