Zoom lens and image pickup apparatus
AssigneeCanon Kabushiki Kaisha
InventorYuki Ikegaya
Life of this patent
Estimating the term…
Abstract
Provided is a zoom lens including: positive first unit; negative second unit; aperture stop; positive third unit; positive fourth unit; and rear lens group including at least one lens unit, wherein the fourth unit includes a positive lens, and wherein an amount of movement of the fourth unit during zooming from wide angle end to telephoto end, distances between the aperture stop and the fourth unit at the wide angle end and between the aperture stop and the fourth unit at the telephoto end, focal lengths of the fourth unit and of the zoom lens at the wide angle end, a length of the zoom lens at the wide angle end, an Abbe number of material of the positive lens with respect to d-line, and a partial dispersion ratio of the material of the positive lens with respect to g-line and F-line are each appropriately set.
Claims14
A zoom lens comprising, 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;
- an aperture stop;
- a third lens unit having a positive refractive power;
- a fourth lens unit having a positive refractive power;
- and
- a rear lens group including at least one lens unit,
- wherein an interval between each pair of adjacent lens units is changed during zooming,
- wherein the fourth lens unit includes a positive lens, and
- wherein the following conditional expressions are satisfied:
- 0.2<−m4/Lw<1.0;
- 0.1<(Ds4w−Ds4t)/Lw<0.2;
- 3.0<f4/fw<4.5;
- and
- 0.0<θgFp−(0.6438−0.001682×νdp),
- where m4 represents an amount of movement of the fourth lens unit during zooming from a wide angle end to a telephoto end, Ds4w represents a distance between the aperture stop and the fourth lens unit at the wide angle end, Ds4t represents a distance between the aperture stop and the fourth lens unit at the telephoto end, f4 represents a focal length of the fourth lens unit, fw represents a focal length of the zoom lens at the wide angle end, Lw represents a length of the zoom lens at the wide angle end, νdp represents an Abbe number of a material of the positive lens with respect to a d-line, and θgFp represents a partial dispersion ratio of the material of the positive lens with respect to a g-line and an F-line.
An image pickup apparatus comprising:
- a zoom lens;
- and
- a photoelectric conversion element configured to receive an image formed by the zoom lens,
- wherein the zoom lens 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;
- an aperture stop;
- a third lens unit having a positive refractive power;
- a fourth lens unit having a positive refractive power;
- and
- a rear lens group including at least one lens unit,
- wherein an interval between each pair of adjacent lens units is changed during zooming,
- wherein the fourth lens unit includes a positive lens, and
- wherein the following conditional expressions are satisfied:
- 0.2<−m4/Lw<1.0;
- 0.1<(Ds4w−Ds4t)/Lw<0.2;
- 3.0<f4/fw<4.5;
- and
- 0.0<θgFp−(0.6438−0.001682×νdp),
- where m4 represents an amount of movement of the fourth lens unit during zooming from a wide angle end to a telephoto end, Ds4w represents a distance between the aperture stop and the fourth lens unit at the wide angle end, Ds4t represents a distance between the aperture stop and the fourth lens unit at the telephoto end, f4 represents a focal length of the fourth lens unit, fw represents a focal length of the zoom lens at the wide angle end, Lw represents a length of the zoom lens at the wide angle end, νdp represents an Abbe number of a material of the positive lens with respect to a d-line, and θgFp represents a partial dispersion ratio of the material of the positive lens with respect to a g-line and an F-line.
Dependencies are inferred from the claim text.