New Patent: EF 400mm f/4 DO IS II

Canon EF 400mm f4 IS USM

The EF 400mm f/4 DO IS USM lens was announced in 2000. That is a long time we haven’t see the updates on this lens, today Canon published a new patent on EF 400mm f/4 DO IS II USM lens. See the detail below:

Canon EF 400mm f4 DO IS II USM

Interpretation and self-description of the patent literature

  • Patent Publication No. 2013-64858
  • 2013.4.11 Release Date
  • Filing date 2011.9.16

Example 1

  • Focal length f = 392.12mm
  • Fno. 4.12
  • Half angle of ω = 3.16 °
  • Image height Y = 21.64mm
  • 262.14mm length lens
  • BF 69.97mm
  • Two fluorite
  • Materials and anomalous partial dispersion DOE to use, reduce the chromatic aberration
  • Refractive power of the diffractive surface
  • Strong, but can reduce the chromatic aberration of the element itself, flare increases
  • The weaker, other optical element DOE play a role
  • Refractive optical unit
  • DOE anomalous partial dispersion and bonding materials
  • DOE aspherical surface on the opposite side of the
  • Vibration control
  • Inner Focus

via: EG