| 摘要 |
A teleconverter according to the present invention includes a master lens apparatus side mount portion, an image pickup apparatus side mount portion, and a converter lens section having a negative refractive power as a whole. The converter lens section includes in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. The second lens unit is a lens unit in which, three lenses are cemented, and which includes in order from the object side to the image side, a first lens having a negative refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power. The teleconverter satisfies predetermined conditional expressions. |
| 主权项 |
1. A teleconverter comprising:
a master lens apparatus side mount portion on which, a master lens apparatus is mounted; an image pickup apparatus side mount portion on which, an image pickup apparatus main-body is mounted; and a converter lens section having a negative refractive power as a whole, for achieving a lens system having a focal length longer than a focal length of the master lens apparatus, by mounting the master lens apparatus, wherein the converter lens section includes in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, and the second lens unit is a lens unit in which, three lenses are cemented, and which includes in order from the object side to the image side, a first lens having a negative refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power, and the teleconverter satisfies the following conditional expressions (1-2), (2-2), and (3-2)
1.5<|f|/D<5.0 (1-2)−0.5<(r22f+r22r)/(r22f−r22r)<−0.08 (2-2)1.55<n2p<1.65 (3-2) where, f denotes a focal length of an overall system of the converter lens section, D denotes a distance on an optical axis, from a lens surface nearest to an object of the converter lens section up to a lens surface nearest to an image of the converter lens section, r22f denotes a paraxial radius of curvature of an object-side surface of the second lens in the second lens unit, r22r denotes a paraxial radius of curvature of an image-side surface of the second lens in the second lens unit, and n2p denotes a refractive index for a d-line of the second lens in the second lens unit. |
