Canon Patent For 2x Teleconverter With Diffractive Optical Element

Egami (translated) spotted a patent filed by Canon for a 2x teleconverter which incorporates a diffractive optical element.

• Patent Publication No. 2014-145870
  • Published Date 2014.8.14
  • Filing date 2013.1.29
• Example 1
  • Focal length -109.09mm
  • Magnification 2.00x
  • 4 group 9-lens configuration
  • One plane diffraction plane (the first group)
• Master lens
  • Focal length f = 293.76mm
  • Fno. 2.91
  • Half angle ω = 4.21 °
  • Image height Y = 21.64mm
  • The overall length of the lens 275.41mm
  • BF 53.79mm
  • 15 sheets 11 groups lens configuration
  • Protective glass 1
  • Rear filter 1
  • UD 2
  • Fluorite 1
• Canon patents
  • I and the diffraction plane cemented surface of the cemented lens closest to the object side
  • This arrangement can suppress the flare