US 2019/0196160 A1Published application

Zoom lens and image pickup apparatus

AssigneeCanon Kabushiki Kaisha

InventorYuki Ikegaya

Life of this patent

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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

Dependent claims

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.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/222,271Filed 17 Dec 2018
Priority: JP 2017-24501421 Dec 2017
Published: 27 Jun 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G02B 15/16
By axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of…:…
G02B 13/02
Optical objectives specially designed for the purposes specified below: telephoto objectives, i.e. systems of the type + - in which the distance…
G02B 15/1451
Having five groups only: the first group being positive
G02B 15/146
By axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of…:…