Zoom lens with bent optical path and image pickup apparatus using the same

A zoom lens with a bent optical path comprising, in order from the object side to the image side:

• a first lens unit having a positive refractive power;
• a second lens unit having a negative refractive power;
• a rear lens unit group including a plurality of lens units and having a positive refractive power as a whole, wherein
• the first lens unit comprises a reflecting member having a reflecting surface that reflects rays,
• the reflecting member is a reflecting prism having an internal reflecting surface that constitutes the reflecting surface, an object side surface, which is an object side refracting surface, and an image side surface, which is an image side refracting surface,
• the combined refractive power of the portion of the first lens unit that is located on the object side of the reflecting surface is negative,
• the combined refractive power of the portion of the first lens unit that is located on the image side of the reflecting surface is positive,
• the distances between the lens units change during zooming from the wide angle end to the telephoto end, and
• the following conditional expressions (1A), (2A), (3A), and (16A) are satisfied:
• 0.1<f1G/fT<0.8 (1A),
• −0.5<f2G/fT<−0.05 (2A),
• 5.5<β2T/β2W<20 (3A), and
• 1.0<fW/IHmax<1.43 (16A),
• where f1G is the focal length of the first lens unit, f2G is the focal length of the second lens unit, fW is the focal length of the entire zoom lens system at the wide angle end in the state in which the zoom lens is focused at the longest distance, fT is the focal length of the entire zoom lens system at the telephoto end in the state in which the zoom lens is focused at the longest distance, β2T is the lateral magnification of the second lens unit in the state in which the zoom lens is focused at the longest distance at the telephoto end, β2W is the lateral magnification of the second lens unit in the state in which the zoom lens is focused at the longest distance at the wide angle end, and IHmax is the image height in the zoom lens with a bent optical path or the highest image height in the case where the image height varies.

A zoom lens with a bent optical path comprising, in order from the object side to the image side:

• a first lens unit having a positive refractive power;
• a second lens unit having a negative refractive power;
• a rear lens unit group including a plurality of lens units and having a positive refractive power as a whole, wherein
• the first lens unit comprises a reflecting member having a reflecting surface that reflects rays,
• the reflecting member is a reflecting prism having an internal reflecting surface that constitutes the reflecting surface, an object side surface, which is an object side refracting surface, and an image side surface, which is an image side refracting surface,
• the combined refractive power of the portion of the first lens unit that is located on the object side of the reflecting surface is negative,
• the combined refractive power of the portion of the first lens unit that is located on the image side of the reflecting surface is positive,
• the rear lens unit group comprises, in order from the object side to the image side, an object side sub lens unit group and an image side lens unit in which all the gaps between the lens elements are constant,
• the distances between the lens units change during zooming from the wide angle end to the telephoto end, and
• the following conditional expressions (5A), (6A), (7A), and (8A) are satisfied:
• 0.1<f1G/fT<0.38 (5A)
• −0.18<f2G/fT<−0.09 (6A)
• 7<(β2T×βRFT)/(β2W×βRFW)<20 (7A), and
• 2.1<P/fW<3.1 (8A),
• where f1G is the focal length of the first lens unit, f2G is the focal length of the second lens unit, fW is the focal length of the entire zoom lens system at the wide angle end in the state in which the zoom lens is focused at the longest distance, fT is the focal length of the entire zoom lens system at the telephoto end in the state in which the zoom lens is focused at the longest distance, β2T is the lateral magnification of the second lens unit in the state in which the zoom lens is focused at the longest distance at the telephoto end, β2W is the lateral magnification of the second lens unit in the state in which the zoom lens is focused at the longest distance at the wide angle end, βRFT is the lateral magnification of the object side sub lens unit group in the state in which the zoom lens is focused at the longest distance at the telephoto end, βRFW is the lateral magnification of the object side sub lens unit group in the state in which the zoom lens is focused at the longest distance at the wide angle end, and P is the actual distance along the optical axis from the object side surface to the image side surface of the reflecting member in the first lens unit.

A zoom lens with a bent optical path comprising, in order from the object side to the image side:

• a first lens unit having a positive refractive power;
• a second lens unit having a negative refractive power;
• a third lens unit having a positive refractive power;
• a fourth lens unit having a negative refractive power;
• and
• a fifth lens unit having a positive refractive power, wherein
• the total number of lens units in the zoom lens with a bent optical path is five,
• the first lens unit comprises a reflecting member having a reflecting surface that reflects rays,
• the distances between the lens units change during zooming from the wide angle end to the telephoto end,
• the third lens unit comprises one cemented lens component comprising three lenses including a positive lens and a negative lens,
• the refractive surface closest to the object side and the refractive surface closest to the image side of the cemented lens component are convex surfaces,
• one negative lens in the cemented lens component is a biconcave lens, which has the smallest Abbe constant among the lenses in the cemented lens component.