Archive for: EF 400 f/4 DO IS

Patent: More DO Supertelephoto Lenses

DO appears to still be alive
More patents for large Canon DO lenses. The one of note is the 500 f/5.6, a lens that would be a very solid follow-up to the EF 400 f/4 DO IS.

We’ve seen a lot of these patents in the past, and none of them have ever come to market. It is good to see R&D is still going into DO technology, as I really enjoy the 400 DO.

50056dopatent

Source: [EG] via [NL]

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Patent: EF 400 f/4 DO IS II

Patent: EF 400 f/4 DO IS II

Another DO patent
We haven’t seen a new DO lens in a long time, but the patents haven’t stopped. It looks like Canon is continuing the R&D, I’d love to see it go somewhere.

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

Source: [EG] | Canon EF 400 f/4 DO IS