Wide-angle converter lens
AssigneeCanon Kabushiki Kaisha
InventorsShoichi Takemoto, Masao Hori, Kazuya Shimomura, Yotaro Sanjo
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Abstract
A wide-angle converter lens capable of being detachably mounted on an enlargement side of an imaging lens includes a first optical element, at least one optical element having negative refractive power, and at least one optical element having positive refractive power, wherein, when an average value of relative partial dispersions of the first optical element and all optical elements of which the sign of refractive power is the same as that of the first optical element is denoted by θgF_ave, a relative partial dispersion of the first optical element is denoted by θgF, and an Abbe number of the first optical element is denoted by νd, these numerical values satisfy appropriate relationships.
Claims18
A wide-angle converter lens capable of being detachably mounted on an enlargement side of an imaging lens, the wide-angle converter lens comprising:
- a first optical element;
- at least one optical element having negative refractive power;
- and
- at least one optical element having positive refractive power,
- wherein, when an average value of relative partial dispersions of the first optical element and all optical elements of which the sign of refractive power is the same as that of the first optical element is denoted by θgF_ave, a relative partial dispersion of the first optical element is denoted by θgF1, and an Abbe number of the first optical element is denoted by νd1, the following conditions are satisfied:
- θgF—ave>0.58
- θgF1−(2.35×10−3×νvd12−4.11×10−3×νd1+0.7204)>0
- νd1<30.
Dependencies are inferred from the claim text.