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 MichaelDanielHo.com 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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