Canon filed a new patent for a new Lens Extender EF2x that employs DOE ( possibly enhanced diffractive optical element ) that minimizes Spherical aberration, astigmatism, other distortion and chromatic aberration caused by magnification of the lens extender.
Lens Patent Details
Explanation and self-interpretation of the patent literature
Patent Publication No. 2014-145870
Published 2014.8.14
Filing date 2013.1.29
Example 1
- Focal length -109.09mm
- Magnification 2.00x
- Lens configuration 4 group nine
- Diffractive surface 1 surface (the first group)
Master lens
- Focal length f = 293.76mm
- Fno. 2.91
- Half angle of ω = 4.21 °
- Image height Y = 21.64mm
- Lens length 275.41mm
- BF 53.79mm
- Lens configuration 11 group 15 sheets
- Protective glass 1
- Rear filter 1
- UD 2
- Fluorite 1
Canon patent of
- The most the joint surface on the object side of the cemented lens I to the diffraction plane
- This arrangement can suppress the flare
via-egami
Un vieux serpent de mer qui réapparaît !
Là, Canon marque des points dans la recherche. Bravo !