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Sunday, April 14, 2013

Canon Patent - EF 400mm f/4L DO IS II Lens

Egami, the Japanese Photography Blog has discovered a new Canon patent on the EF 400mm DO lens. This is one of my favorite glass in Canon's EF lens lineup. You can read the original article in Japanese here. Check out my earlier post on Canon Lens Recommendation and visit my website to see many photos taken with the fantastic EF 400mm f/4L DO IS lens.

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

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