Canon Patent: 500mm f/4 & f/5.6, 600mm f/4, 800mm f/5.6

Egami (translated) spotted a patent filed by Canon regarding 500mm f/4, 500mm f/5.6, 600mm  f/4 and 800mm f/5.6 lenses.

• Patent Publication No. 2013-92575
  • Publication date 2013.5.16
  • Filing date 2011.10.24
• Example
  

  embodiment

  No.	Focal length [mm]	Fno.	Half angle [°]	Total length [mm]	BF [mm]	Front lens diameter [mm]
  One	584.99	4.12	2.12	420.00	89.03	141.99
  Two	779.99	5.80	1.59	460.00	97.84	134.48
  Three	488.99	4.11	2.53	320.00	61.00	119.00
  Four	488.99	5.70	2.53	280.01	65.01	85.79
  Five	584.96	4.12	2.12	420.00	88.88	141.98

  Image height 21.64mm

• How to reduce the size of the large-aperture super telephoto lens
  • Effective diameter of the first group with the largest
  • I reduce the number of the first group
    • It is necessary to reduce aberration by increasing the number
    • Can not reduce the aberration and reduce the number
  • I increase a refractive power of the first group
    • The thickness of the lens increases, the effect of weight reduction is canceled
    • Impact of manufacturing error is large high refractive index
• Canon patent
  • The aspherical in the first group
  • Performing a variance of sensitivity was composed of opposite sign component of the first group, and also, prevent an increase in thickness
  • DOE is provided to correct chromatic aberration with a small number of lenses
  • Inner focus
  • Anti-shake