Zoom lens and image pickup apparatus

An image pickup apparatus comprising:

• a zoom lens;
• and
• an image pickup element configured to receive an image formed by the zoom lens,
• wherein the zoom lens comprising:
• a master lens including in order from an object side to an image side:
• a first lens unit having a positive refractive power and configured not to move for zooming;
• a second lens unit having a negative refractive power and configured to move for zooming;
• at least one lens unit configured to move for zooming;
• and
• a relay lens unit having a positive refractive power and arranged closest to the image side;
• and
• an extender lens unit configured to be insertable into or removable from an optical path of the zoom lens between the at least one lens unit and the relay lens unit to extend a focal length of the zoom lens by one of:
• being inserted in place of a lens unit arranged adjacent to the relay lens unit;
• and being inserted into a space adjacent to the relay lens unit,
• wherein the extender lens unit includes a positive lens Gp, and the positive lens Gp satisfies conditional expressions
• θgF−(−1.6650×10−7·νd3+5.2130×10−5·νd2−5.6560×10−3·νd+0.7370)>0;
• 0.5450<θgF;
• and
• 50.0<νd<85.0,
• where νd and θgF represent an Abbe number and a partial dispersion ratio of the positive lens (Gp), respectively, and
• wherein an Abbe number νd and a partial dispersion ratio θgF of a material are expressed by expressions
• νd=(Nd−1)/(NF−NC);
• and
• θgF=(Ng−NF)/(NF−NC),respectively,
• where Ng, NF, NC, and Nd represent refractive indices of the material with respect to a g-line (wavelength of 435.8 nm), an F-line (wavelength of 486.1 nm), a C-line (wavelength of 656.3 nm), and a d-line (wavelength of 587.6 nm), respectively.

An extender lens unit configured to be insertable into or removable from an optical path of an image pickup apparatus to extend a focal length of the image pickup apparatus,

• wherein the extender lens unit includes a positive lens Gp, and the positive lens Gp satisfies conditional expressions
• θgF−(−1.6650×10−7·νd3+5.2130×10−5·νd2−5.6560×10−3·νd+0.7370)>0;
• 0.5450<θgF;
• and
• 50.0<νd<85.0,
• where νd and θgF represent an Abbe number and a partial dispersion ratio of the positive lens Gp, respectively, and
• wherein an Abbe number νd and a partial dispersion ratio θgF of a material are expressed by expressions
• νd=(Nd−1)/(NF−NC);
• and
• θgF=(Ng−NF)/(NF−NC), respectively,
• where Ng, NF, NC, and Nd represent refractive indices of the material with respect to a g-line (wavelength of 435.8 nm), an F-line (wavelength of 486.1 nm), a C-line (wavelength of 656.3 nm), and a d-line (wavelength of 587.6 nm), respectively.

An image pickup apparatus comprising:

• an extender lens unit;
• and
• an image pickup element configured to receive an image formed via the extender lens unit,
• wherein the extender lens unit includes a positive lens Gp, and the positive lens Gp satisfies conditional expressions
• θgF−(−1.6650×10−7·νd3+5.2130×10−5·νd2−5.6560×10−3·νd+0.7370)>0;
• 0.5450<θgF;
• and
• 50.0<νd<85.0,
• where νd and θgF represent an Abbe number and a partial dispersion ratio of the positive lens Gp, respectively, and
• wherein an Abbe number νd and a partial dispersion ratio θgF of a material are expressed by expressions
• νd=(Nd−1)/(NF−NC);
• and
• θgF=(Ng−NF)/(NF−NC), respectively,
• where Ng, NF, NC, and Nd represent refractive indices of the material with respect to a g-line (wavelength of 435.8 nm), an F-line (wavelength of 486.1 nm), a C-line (wavelength of 656.3 nm), and a d-line (wavelength of 587.6 nm), respectively.