Zoom lens and optical instrument using the same

• US 6,671,104 B2
• Filed: 12/17/2001
• Issued: 12/30/2003
• Est. Priority Date: 12/22/2000
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Endo, Hiroshi
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Collins, Darryl J.
• Application Number:
  US10/016,115
• Publication Number:
  US 20020196560A1
• Time in Patent Office: 743 Days
• Field of Search: 359/683, 359/686, 359/689, 359/691
• US Class Current: 359/691
• CPC Class Codes: G02B 15/1425 the first group being negative
• CPC Class Codes: G02B 15/143503 arranged -+-
• CPC Class Codes: G02B 15/143505 arranged --+
• CPC Class Codes: G02B 15/16 with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group G02B15/22 takes precedence
• CPC Class Codes: G02B 15/177 having a negative front lens or group of lenses

Abstract

A negative-lead type zoom lens has a diffractive optical element and is led by a lens unit having a negative optical power. In this zoom lens, various kinds of aberration including chromatic aberration are excellently corrected by properly setting the lens configuration of each lens unit so as to achieve high optical performance over the entire range of a variable power while the entire lens system is miniaturized and designed to have a wide angle. The zoom lens according to the present invention is suitable for a zoom lens with a wide angle including a wide-angle region that is a focal length of substantially 28 mm on a 35 mm single lens reflex camera basis.

Claims

1. A zoom lens comprising:

a first lens system having an overall negative power and comprising at least two negative lens elements and at least one positive lens element; and

a second lens unit, disposed behind the first lens system, having a positive power and comprising at least two positive lens elements and at least one negative lens element,

wherein during zooming, at least the second lens unit is moved so that the space between the first lens system and the second lens unit is changed, and at least one of the first lens system and the second lens unit comprises a diffractive optical element,

wherein the following conditions are satisfied;

2. A zoom lens according to claim 1, wherein the first lens system comprises the diffractive optical element, and the optical power only due to diffraction of the diffractive optical element included in the first lens system is negative.

3. A zoom lens according to claim 1, wherein the second lens unit comprises the diffractive optical element, and the optical power only due to diffraction of the diffractive optical element included in the second lens unit is positive.

4. A zoom lens according to claim 1, wherein the second lens unit comprises an aperture diaphragm.

5. A zoom lens according to claim 1, wherein the following conditions are satisfied:

6. A zoom lens according to claim 1, wherein the following condition is satisfied:

7. A zoom lens according to claim 1, wherein a diffractive portion of the diffractive optical element is provided with a plurality of layers of diffraction gratings.

8. An optical instrument comprising:

an optical element; and

a zoom lens according to claim 1, connected to said optical element.

9. An image pick-up apparatus comprising:

a zoom lens according to claim 1; and

a photoelectric conversion element for receiving an image formed by the zoom lens.

10. A zoom lens according to claim 1, wherein the second lens unit comprises the diffractive optical element, which is disposed at the most image side of the second lens unit.

11. A zoom lens according to claim 10, wherein the diffractive optical element of the second lens unit comprises a lens and a diffraction surface disposed thereupon.

12. A zoom lens according to claim 11, wherein the diffraction surface is disposed on the image side of the lens of the diffractive optical element.

13. A zoom lens according to claim 11, wherein the lens of the diffractive optical element is a positive lens.

14. A zoom lens according to claim 1, wherein the first lens system consists of a negative lens unit.

15. A zoom lens comprising:

a first lens system having an overall negative power and comprising at least two negative lens elements and at least one positive lens element; and

a second lens unit, disposed behind the first lens system, having a positive power and comprising at least two positive lens elements and at least one negative lens element,

wherein during zooming, at least the second lens unit is moved so that the space between the first lens system and the second lens unit is changed, and at least one of the first lens system and the second lens unit comprises a diffractive optical element,

wherein the following conditions are satisfied;

16. A zoom lens comprising:

a first lens unit having a negative optical power;

a second lens unit having a negative optical power; and

a third lens unit having a positive optical power, from an object side in that order,

wherein during zooming, the spaces between the first lens unit and the second lens unit and between the second lens unit and the third lens unit are changed, and

wherein at least one of the first lens unit, the second lens unit, and the third lens unit comprises a diffractive optical element.

17. A zoom lens according to claim 16, wherein the following condition is satisfied:

18. A zoom lens according to claim 16, wherein the first lens unit comprises the diffractive optical element and the optical power only due to diffraction of the diffractive optical element included in the first lens unit is negative.

19. A zoom lens according to claim 16, wherein the third lens unit comprises the diffractive optical element and an optical power only due to diffraction of the diffractive optical element included in the third lens unit is positive.

20. A zoom lens according to claim 16, wherein the third lens unit comprises an aperture diaphragm.

21. A zoom lens according to claim 16, wherein the following conditions are satisfied:

22. A zoom lens according to claim 16, wherein the following condition is satisfied:

23. A zoom lens according to claim 16, wherein the following condition is satisfied:

24. A zoom lens according to claim 16, wherein a diffractive portion of the diffractive optical element is provided with a plurality of layers of diffraction gratings.

25. An optical instrument comprising:

an optical element and

a zoom lens according to claim 16 connected to said optical element.

26. An image pick-up apparatus comprising:

a zoom lens according to claim 16; and

a photoelectric conversion element for receiving an image formed by the zoom lens.

27. A zoom lens comprising:

a first lens system having an overall negative power and comprising at least two negative lens elements and at least one positive lens element; and

a second lens unit, disposed behind the first lens system, having a positive power and comprising at least two positive lens elements and at least one negative lens element,

wherein during zooming, at least the second lens unit is moved so that the space between the first lens system and the second lens unit is changed, and at least one of the first lens system and the second lens unit comprises a diffractive optical element,

wherein the following conditions are satisfied;

28. A zoom lens comprising:

a first lens system having an overall negative power and comprising at least two negative lens elements and at least one positive lens element; and

a second lens unit, disposed behind the first lens system, having a positive power and comprising at least two positive lens elements and at least one negative lens element,

wherein during zooming, at least the second lens unit is moved so that the space between the first lens system and the second lens unit is changed, and at least one of the first lens system and the second lens unit comprises a diffractive optical element,

wherein the following conditions are satisfied;

29. A zoom lens according to claim 28, wherein one of the two negative lens units is stationary during zooming, and the other of the two negative lens units moves during zooming.

30. A zoom lens comprising:

a first lens system having an overall negative power and comprising at least two negative lens elements and at least one positive lens element; and

a second lens unit, disposed behind the first lens system, having a positive power and comprising at least two positive lens elements and at least one negative lens element,

wherein during zooming, at least the second lens unit is moved so that the space between the first lens system and the second lens unit is changed, and at least one of the first lens system and the second lens unit comprises a diffractive optical element,

wherein the following conditions are satisfied;

31. A zoom lens comprising:

a first lens system having an overall negative power and comprising at least two negative lens elements and at least one positive lens element; and

a second lens unit, disposed behind the first lens system, having a positive power and comprising at least two positive lens elements and at least one negative lens element,

wherein during zooming, at least the second lens unit is moved so that the space between the first lens system and the second lens unit is changed, and at least one of the first lens system and the second lens unit comprises a diffractive optical element,

wherein the following conditions are satisfied;