Zoom optical system and camera using the same

A zoom optical system comprising, in order from an object side:

• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• a third lens unit having negative refractive power;
• and
• an aperture stop disposed on an image side of said second lens unit,
• wherein a magnification is changed from wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit, and wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.5<fG1/fW<1.35 0.2<|fG3/fW|<0.5
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position,
• a reference symbol fG1 represents a focal length of the first lens unit, and
• a reference symbol fG3 represents a focal length of the third lens unit.

A zoom optical system comprising, in order from an object side:

• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• a third lens unit having negative refractive power;
• and
• an aperture stop disposed on an image side of said second lens unit,
• wherein a magnification is changed from a wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit,
• wherein said second lens unit comprises a bi-concave lens element disposed on the most object side and at least two positive lens elements, and said second lens unit comprises two lens components or three lens components in all the second lens unit, and
• wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.2<|fG3/fW|<0.48
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position, and
• a reference symbol fG3 represents a focal length of the third lens unit.

A camera comprising;

• a photographic system including a zoom optical system;
• and
• a field stop for determining an image area located on an image side of said zoom optical system,
• wherein the zoom optical system comprises, in order from an object side:
• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• and
• a third lens unit having negative refractive power,
• wherein a magnification is changed from a wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit, and wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.5<fG1/fW<1.45 0.8<fG2/fW<1.2 0.4<|fG3/fW<0.5
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position,
• a reference symbol fG1 represents a focal length of the first lens unit,
• a reference symbol fG2 represents a focal length of the second lens unit, and
• a reference symbol fG3 represents a focal length of the third lens unit.

A camera comprising;

• a photographic system including a zoom optical system;
• and
• a field stop for determining an image area located on an image side of said zoom optical system,
• wherein the zoom optical system comprises, in order from an object side:
• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• a third lens unit having negative refractive power;
• and
• an aperture stop disposed on an image side of said second lens unit,
• wherein a magnification is changed from wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit, and wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.5<fG1/fW<1.35 0.2<|fG3/fW|<0.5
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position,
• a reference symbol fG1 represents a focal length of the first lens unit, and
• a reference symbol fG3 represents a focal length of the third lens unit.

A camera comprising;

• a photographic system including a zoom optical system;
• and
• a field stop for determining an image area located on an image side of said zoom optical system,
• wherein a zoom optical system comprises, in order from an object side:
• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• a third lens unit having negative refractive power;
• and
• an aperture stop disposed on an image side of said second lens unit, wherein a magnification is changed from a wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit,
• wherein said second lens unit comprises a bi-concave lens element disposed on the most object side and at least two positive lens elements, and said second lens unit comprises two lens components or three lens components in all the second lens unit, and
• wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.2<|fG3/fW|<0.48
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position, and
• a reference symbol fG3 represents a focal length of the third lens unit.

A zoom optical system comprising, in order from an object side:

• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• and
• a third lens unit having negative refractive power,
• wherein a magnification is changed from a wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit,
• wherein said first lens unit comprises, in order from the object side, a negative meniscus lens component having a concave surface facing toward the object side and a bi-convex lens component, and
• wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.5<fG1/fW<1.5 0.8<fG2/fW<1.2 0.2<|fG3/fW|<0.5
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position,
• a reference symbol fG1 represents a focal length of the first lens unit,
• a reference symbol fG2 represents a focal length of the second lens unit, and
• a reference symbol fG3 represents a focal length of the third lens unit.

A zoom optical system comprising, in order from an object side:

• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• a third lens unit having negative refractive power;
• and
• an aperture stop disposed on an image side of said second lens unit,
• wherein a magnification is changed from wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit,
• wherein said first lens unit comprises, in order from the object side, a negative meniscus lens component having a concave surface facing toward the object side and a bi-convex lens component, and
• wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.5<fG1/fW<1.5 0.2<|fG3/fW|<0.5
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position,
• a reference symbol fG1 represents a focal length of the first lens unit, and
• a reference symbol fG3 represents a focal length of the third lens unit.

A zoom optical system comprising, in order from an object side:

• a first lens unit having positive refractive power;
• a second lens unit having positive refractive power;
• a third lens unit having negative refractive power;
• and
• an aperture stop disposed on an image side of said second lens unit,
• wherein a magnification is changed from a wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between said first lens unit and said second lens unit and narrow an airspace between said second lens unit and said third lens unit,
• wherein said first lens unit comprises, in order from the object side, a negative meniscus lens component having a concave surface facing toward the object side and a bi-convex lens component,
• wherein said second lens unit comprises a bi-concave lens element disposed on the most object side and at least two positive lens elements, and said second lens unit comprises two lens components or three lens components in all the second lens unit, and
• wherein said zoom optical system satisfies the following conditions:
• 0.5<LT/fT<0.8 0.2<|fG3/fW|<0.5
• where a reference symbol fW represents a focal length of the zoom optical system at the wide-angle position,
• a reference symbol fT represents a focal length of the zoom optical system at the telephoto position,
• a reference symbol LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position, and
• a reference symbol fG3 represents a focal length of the third lens unit.