US 7,443,599 B2Granted

Magnification varying optical system and image taking apparatus

AssigneeKonica Minolta Opto, Inc.

InventorsTetsuo Kohno, Mamoru Terada, Yoshihito Souma

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Abstract

A magnification varying optical system that directs light from an object to an image sensor includes in order from the object side: a first lens unit having negative optical power and including an optical axis changing element that changes the optical axis; a second lens unit having positive optical power and including three lens elements; a third lens unit having negative optical power; and a fourth lens unit having positive optical power. In this magnification varying optical system, in magnification varying from the wide-angle end to the telephoto end, the first lens unit is stationary, the distance from the first lens unit to the second lens unit decreases, and the distance from the third lens unit to the fourth lens unit increases. The magnification varying optical system satisfies the specified conditions.

Claims14

Dependent claims

A magnification varying optical system that directs light from an object to an image sensor, comprising from the object side to an image side:

a first lens unit having negative optical power, and including an optical axis changing element that changes an optical axis;
a second lens unit having positive optical power, and including three lens elements, the second lens unit having:
a positive lens element having a convex surface on the object side, in a most object side position;
a negative lens element;
and
a positive lens element;
a third lens unit having negative optical power;
and
a fourth lens unit having positive optical power,
wherein in magnification varying from a wide-angle end to a telephoto end,
the first lens unit is stationary,
a distance from the first lens unit to the second lens unit decreases, a distance from the third lens unit to the fourth lens unit increases, and
the magnification varying optical system satisfies the following conditions:
−2.0<f—GR1—o/fm<−0.5, and
−1.2<[r—GR2—o+r—GR2—i]/[r—GR2—o−r—GR2—i]<0
where f_GR1_o is a focal length of a lens element situated on the object side of the optical axis changing element in the first lens unit;
fm is (fw×ft)1/2;
fw is an overall focal length of the magnification varying optical system at the wide-angle end;
ft is an overall focal length of the magnification varying optical system at the telephoto end;
r_GR2_o is a radius of curvature of an object side surface of the most object side positive lens element in the second lens unit;
and
r_GR2_i is a radius of curvature of an image side surface of the most object side positive lens element in the second lens unit,
wherein the magnification varying optical system further satisfies the following conditions:
−1.3<f1/fm<−0.5, and
0.5<f2/fm<1.5,
where f1 is a focal length of the first lens unit, and
f2 is a focal length of the second lens unit.

24 more elements

A magnification varying optical system that directs light from an object to an image sensor, comprising from the object side to an image side:

a first lens unit having negative optical power, and including an optical axis changing element that changes an optical axis;
a second lens unit having positive optical power, and including three lens elements, the second lens unit having:
a positive lens element having a convex surface on the object side, in a most object side position;
a negative lens element;
and
a positive lens element;
a third lens unit having negative optical power;
and
a fourth lens unit having positive optical power,
wherein in magnification varying from a wide-angle end to a telephoto end,
the first lens unit is stationary,
a distance from the first lens unit to the second lens unit decreases, a distance from the third lens unit to the fourth lens unit increases, and
the magnification varying optical system satisfies the following conditions:
−2.0<f—GR1—o/fm<−0.5, and
−1.2<[r—GR2—o+r—GR2—i]/[r—GR2—o−r—GR2—i]<0
where f_GR1_o is a focal length of a lens element situated on the object side of the optical axis changing element in the first lens unit;
fm is (fw×ft)1/2;
fw is an overall focal length of the magnification varying optical system at the wide-angle end;
ft is an overall focal length of the magnification varying optical system at the telephoto end;
r_GR2_o is a radius of curvature of an object side surface of the most object side positive lens element in the second lens unit;
and
r_GR2_i is a radius of curvature of an image side surface of the most object side positive lens element in the second lens unit,
wherein the positive lens element in the most object side of the second lens unit has an aspherical surface.

20 more elements

An image taking apparatus comprising:

an image sensor that converts an optical image into an electric signal, and
a magnification varying optical system that forming the optical image of an object, the magnification varying optical system comprising from the object side to an image side:
a first lens unit having negative optical power, and including an optical axis changing element that changes an optical axis;
a second lens unit having positive optical power, and including three lens elements, the second lens unit having:
a positive lens element having a convex surface on the object side, in a most object side position;
a negative lens element;
and
a positive lens element;
a third lens unit having negative optical power;
and
a fourth lens unit having positive optical power,
wherein in magnification varying from a wide-angle end to a telephoto end,
the first lens unit is stationary,
a distance from the first lens unit to the second lens unit decreases, a distance from the third lens unit to the fourth lens unit increases, and
the magnification varying optical system satisfies the following conditions:
−2.0<f—GR1—o/fm<−0.5, and
−1.2<[r—GR2—o+r—GR2—i]/[r—GR2—o−r—GR2—i]<0
where f_GR1_o is a focal length of a lens element situated on the object side of the optical axis changing element in the first lens unit;
fm is (fw×ft)1/2;
fw is an overall focal length of the magnification varying optical system at the wide-angle end;
ft is an overall focal length of the magnification varying optical system at the telephoto end;
r_GR2_o is a radius of curvature of an object side surface of the most object side positive lens element in the second lens unit;
and
r_GR2_i is a radius of curvature of an image side surface of the most object side positive lens element in the second lens unit,
wherein the magnification varying optical system further satisfies the following conditions:
−1.3<f1/fm<−0.5, and
0.5<f2/fm<1.5,
where f1 is a focal length of the first lens unit, and
f2 is a focal length of the second lens unit.

26 more elements

An image taking apparatus comprising:

an image sensor that converts an optical image into an electric signal, and
a magnification varying optical system that forming the optical image of an object, the magnification varying optical system comprising from the object side to an image side:
a first lens unit having negative optical power, and including an optical axis changing element that changes an optical axis;
a second lens unit having positive optical power, and including three lens elements, the second lens unit having:
a positive lens element having a convex surface on the object side, in a most object side position;
a negative lens element;
and
a positive lens element;
a third lens unit having negative optical power;
and
a fourth lens unit having positive optical power,
wherein in magnification varying from a wide-angle end to a telephoto end,
the first lens unit is stationary,
a distance from the first lens unit to the second lens unit decreases, a distance from the third lens unit to the fourth lens unit increases, and
the magnification varying optical system satisfies the following conditions:
−2.0<f—GR1—o/fm<−0.5, and
−1.2<[r—GR2—o+r—GR2—i]/[r—GR2—o−r—GR2—i]<0
where f_GR1_o is a focal length of a lens element situated on the object side of the optical axis changing element in the first lens unit;
fm is (fw×ft)1/2;
fw is an overall focal length of the magnification varying optical system at the wide-angle end;
ft is an overall focal length of the magnification varying optical system at the telephoto end;
r_GR2_o is a radius of curvature of an object side surface of the most object side positive lens element in the second lens unit;
and
r_GR2_i is a radius of curvature of an image side surface of the most object side positive lens element in the second lens unit,
wherein the positive lens element in the most object side of the second lens unit has an aspherical surface.

22 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/709,529Filed 22 Feb 2007
Priority: JP 2006-05352728 Feb 2006
Published: US 2007/0201143 A130 Aug 2007
Granted: 28 Oct 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G02B 9/34
Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -: having four…
G02B 15/144511
The first group being negative: arranged -+-+
G02B 15/177
With interdependent non-linearly related movements between one lens or lens group, and another lens or lens group: having a negative front lens or…
G02B
Optical elements, systems or apparatus