Canon Patent For 600mm f/4 Lens

Egami (translated) spotted a patent filed by Canon for a new 600mm f/4 lens. Egami suggests the lens will be ready for Tokyo Olympic Games in 2020 and the Rio de Janeiro Olympic Games in 2016.

• Patent Publication No. 2014-26210
  • Publication date 2014.2.6
  • Filing date 2012.7.30
• Example 1
  • Focal length f = 588mm
  • Fno. 4.12
  • Angle of view 2ω = 4.22 °
  • BF 56.0mm
  • Total lens length 374.7mm
  • Inner focus
• Example 5
  • Focal length f = 588mm
  • Fno. 4.12
  • Angle of view 2ω = 4.22 °
  • BF 55.0mm
  • Total lens length 343.5mm
  • Inner focus
  • Diffraction optical element
• Effect of the glass material
  • Fluorite (Fluorite)
    • In the long lens fluorite + total length, correction of chromatic aberration is easy
    • In short lens fluorite + total length, correction of chromatic aberration is difficult
  • Diffractive optical element (DOE)
    • Diffractive optical element can be corrected if the chromatic aberration
    • Flare caused by light diffraction