Optical assembly for a wide field of view point action camera with a low sag aspheric lens element

1. An optical assembly for a point action camera having a wide field of view, comprising multiple lens elements, including an aspheric surface with an approximately 30 microns or less sag and an approximately 25 microns/millimeter or less aspheric sag slope, configured to provide a field of view in excess of 150 degrees, and

wherein the optical assembly comprises from object end to image end a first optical group and a second optical group, wherein the first optical group is configured to collect light at said wide field of view and said second optical group is configured to correct distortion error, and

wherein said aspheric surface to correct astigmatism error, and

wherein said aspheric surface includes a point of inflection of aspheric slope extremum at a radial distance from a center of said aspheric surface that is less than approximately 0.5× a center to edge radius of said aspheric surface.

2. The optical assembly of claim 1 , wherein said aspheric sag comprises less than approximately 25 microns.

3. The optical assembly of claim 1 , wherein said aspheric sag comprises less than approximately 23 microns.

4. The optical assembly of claim 1 , wherein said aspheric sag comprises less than approximately 21 microns.

5. The optical assembly of claim 1 , wherein said aspheric sag slope comprises less than approximately 25 microns per millimeter.

6. The optical assembly of claim 1 , wherein said aspheric sag slope comprises less than approximately 20 microns per millimeter.

7. The optical assembly of claim 1 , wherein said aspheric sag slope comprises less than approximately 15 microns per millimeter.

8. The optical assembly of claim 1 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.8× a center to edge radius of said aspheric surface.

9. The optical assembly of claim 1 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.75× a center to edge radius of said aspheric surface.

10. The optical assembly of claim 1 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.7× a center to edge radius of said aspheric surface.

11. The optical assembly of claim 1 , wherein said point of inflection of aspheric slope extremum at less than approximately 0.4× a center to edge radius of said aspheric surface.

12. The optical assembly of claim 1 , wherein said point of inflection of aspheric slope extremum at less than approximately 0.3× a center to edge radius of said aspheric surface.

13. The optical assembly of claim 1 , wherein said optical assembly comprises seven lens elements.

14. The optical assembly of claim 1 , wherein said second optical group comprises four lens elements.

15. The optical assembly of claim 1 , wherein said second optical group comprises from object side to image side, a first singlet, a doublet and a second singlet.

16. The optical assembly of claim 15 , wherein said first singlet comprises a biconvex or plano-convex or quasi-plano-convex lens.

17. The optical assembly of claim 16 , wherein said second singlet comprises a biconvex, or convexo-plano or convexo-quasi-plano lens.

18. The optical assembly of claim 17 , wherein said first optical group comprises two or more convexo-concave or meniscus lenses.

19. The optical assembly of claim 18 , wherein said first optical group further comprises a biconvex lens.

20. The optical assembly of claim 15 , wherein said doublet comprises, from object side to image side, a biconcave lens and a biconvex lens.

21. The optical assembly of claim 15 , further comprising a third optical group disposed between the first and second optical groups.

22. The optical assembly of claim 21 , wherein the third optical group comprises a biconvex lens.

23. The optical assembly of claim 1 , wherein the lateral chromatic aberration is less than approximately three pixels.

24. The optical assembly of claim 23 , wherein the lateral chromatic aberration is less than approximately two pixels.

25. The optical assembly of claim 1 , wherein the lateral chromatic aberration is less than approximately five microns.

26. The optical assembly of claim 25 , wherein the lateral chromatic aberration is less than approximately three microns.

27. A digital camera, comprising

an optical assembly as in claim 1 ; and

an image sensor disposed approximately at a focal plane of the optical assembly; and

a digital camera housing including electronics and a user interface, and containing said optical assembly and said image sensor in optically effective relative disposition.

28. The digital camera of claim 27 , wherein said aspheric sag comprises less than approximately 25 microns.

29. The digital camera of claim 27 , wherein said aspheric sag comprises less than approximately 23 microns.

30. The digital camera of claim 27 , wherein said aspheric sag comprises less than approximately 21 microns.

31. The digital camera of claim 27 , wherein said aspheric sag slope comprises less than approximately 25 microns per millimeter.

32. The digital camera of claim 27 , wherein said aspheric sag slope comprises less than approximately 20 microns per millimeter.

33. The digital camera of claim 27 , wherein said aspheric sag slope comprises less than approximately 15 microns per millimeter.

34. The digital camera of claim 27 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.8× a center to edge radius of said aspheric surface.

35. The digital camera of claim 27 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.75× a center to edge radius of said aspheric surface.

36. The digital camera of claim 27 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.7× a center to edge radius of said aspheric surface.

37. The digital camera of claim 27 , wherein said point of inflection of aspheric slope extremum at less than approximately 0.4× a center to edge radius of said aspheric surface.

38. The digital camera of claim 27 , wherein said point of inflection of aspheric slope extremum at less than approximately 0.3× a center to edge radius of said aspheric surface.

39. The digital camera of claim 27 , wherein said optical assembly comprises seven lens elements.

40. The digital camera of claim 27 , wherein said second optical group comprises four lens elements.

41. The digital camera of claim 27 , wherein said second optical group comprises from object side to image side, a first singlet, a doublet and a second singlet.

42. The digital camera of claim 41 , wherein said first singlet comprises a biconvex or plano-convex or quasi-plano-convex lens.

43. The digital camera of claim 42 , wherein said second singlet comprises a biconvex, or convexo-plano or convexo-quasi-plano lens.

44. The digital camera of claim 43 , wherein said first optical group comprises two or more convexo-concave or meniscus lenses.

45. The digital camera of claim 44 , wherein said first optical group further comprises a biconvex lens.

46. The digital camera of claim 41 , wherein said doublet comprises, from object side to image side, a biconcave lens and a biconvex lens.

47. The digital camera of claim 41 , further comprising a third optical group disposed between the first and second optical groups.

48. The digital camera of claim 47 , wherein the third optical group comprises a biconvex lens.

49. The digital camera of claim 27 , wherein the lateral chromatic aberration is less than approximately three pixels.

50. The digital camera of claim 49 , wherein the lateral chromatic aberration is less than approximately two pixels.

51. The digital camera of claim 27 , wherein the lateral chromatic aberration is less than approximately five microns.

52. The digital camera of claim 51 , wherein the lateral chromatic aberration is less than approximately three microns.

53. An aspheric lens element for an optical assembly of a wide field of view point action camera, comprising an aspheric surface with an approximately 30 microns or less sag and an approximately 25 microns/millimeter or less aspheric sag slope, and

wherein said aspheric surface includes a point of inflection of aspheric slope extremum at a radial distance from a center of said aspheric surface that is less than approximately 0.5× a center to edge radius of said aspheric surface.

54. The aspheric lens element of claim 53 , wherein said aspheric sag comprises less than approximately 25 microns.

55. The aspheric lens element of claim 53 , wherein said aspheric sag comprises less than approximately 23 microns.

56. The aspheric lens element of claim 53 , wherein said aspheric sag comprises less than approximately 21 microns.

57. The aspheric lens element of claim 53 , wherein said aspheric sag slope comprises less than approximately 25 microns per millimeter.

58. The aspheric lens element of claim 53 , wherein said aspheric sag slope comprises less than approximately 20 microns per millimeter.

59. The aspheric lens element of claim 53 , wherein said aspheric sag slope comprises less than approximately 15 microns per millimeter.

60. The aspheric lens element of claim 53 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.8× a center to edge radius of said aspheric surface.

61. The aspheric lens element of claim 53 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.75× a center to edge radius of said aspheric surface.

62. The aspheric lens element of claim 53 , wherein said aspheric surface includes a point of maximum sag at less than approximately 0.7× a center to edge radius of said aspheric surface.

63. The aspheric lens element of claim 53 , wherein said point of inflection of aspheric slope extremum at less than approximately 0.4× a center to edge radius of said aspheric surface.

64. The aspheric lens element of claim 53 , wherein said point of inflection of aspheric slope extremum at less than approximately 0.3× a center to edge radius of said aspheric surface.