Egami has discovered a new patent filed by Canon. Canon patent for the EF 400mm DO lens. Original article in Japanese for the new Canon patent can be read here. Below are the details for the EF 400mm f/4L DO IS lens patent details.
Canon EF 400mm f/4L DO IS Lens Patent
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
