A zoom relay system includes an optical element for receiving light from an object. The zoom relay system is adapted to generate an image of the object on an image plane. The system includes a single varifocal lens group positioned along an optical axis. The varifocal lens group includes at least one lens for providing magnification and a varifocal freeform lens including two lens plates. The lens plates are configured to be disposed along a dimension transverse to the optical axis, such that, when the varifocal lens group is moved along the optical axis to adjust the magnification, the lens plates of the varifocal freeform lens are displaced in the transverse dimension relative to each other to provide compensation, such that, when the magnification is changed, a distance between the object and the image plane remains constant.

There is described an apparatus comprising a first optical element, a second optical element and a spacing element for use with a mobile user device. The first optical element is configured to provide an image of an object to an intermediate image plane and the second optical element magnifies the image to provide a final image in a final image plane in which a camera aperture of the device is supported. The spacing element maintains a fixed separation between the object and the first optical element. Image magnification is achieved while also providing a space for tool access. Mirrors may be used to divert the optical path, allowing the optical path to be folded for more compact apparatus. A third optical element disposed at the intermediate image plane may be used to reduce vignetting effects in the final image.

An image capturing lens system includes three lens groups including five lens elements. The three lens groups are, in order from an object side to an image side: first, second and third lens groups. The five lens elements are, in order from the object side to the image side: first, second, third, fourth and fifth lens elements. The first lens element has an object-side surface being convex in a paraxial region thereof. The second lens element has negative refractive power. At least one lens element has an inflection point. A focal length of the image capturing lens system is varied by changing axial distances between the three lens groups in a zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end. The second lens group is moved relative to the first lens group along an optical axis in the zooming process.

A control apparatus includes an acquirer (129a) that acquires a first signal and a second signal that correspond to output signals of a first photoelectric converter and a second photoelectric converter, respectively, the first and second photoelectric converters receiving light beams passing through different pupil regions of an image capturing optical system from each other, and a calculator (129b) that calculates a correlation value of the first signal and the second signal to calculate a defocus amount based on the correlation value, and the calculator corrects the correlation value based on a light receiving amount of at least one of the first photoelectric converter and the second photoelectric converter.

An optical imaging system includes a first lens group, a second lens group, and a third lens group, sequentially arranged from an object side, wherein the first lens group includes two lenses having negative and positive refractive power, the second lens group includes a plurality of lenses, and the third lens group includes two lenses having negative and positive refractive power.

An optical system includes a plurality of lenses. The distance from the object side lens surface of a lens arranged an the most object side to the image plane is longer than the focal length of the entire system. The material of a positive lens G1p arranged on the most object side among positive lenses included in the optical system, and the arrangement and material of a negative lens Gn located on the most object side among negative lenses arranged an the image side of the positive lens G1p are appropriately set.

A projection zoom lens assembly for a digital cinema projection system includes three optical groups. A first optical group includes one or more wide angle lenses for projecting digital cinema images. A second optical group includes a set of zoom optical groups each comprising two or more lenses, including a first independently movable zoom group, a second independently movable zoom group, and a third zoom group. A third optical group includes multiple lenses for receiving images for projection.

This disclosure describes an afocal attachment that allows for alteration of received electromagnetic radiation (or “light”) prior to entry into the telescope. For example, a rifle scope may have a base magnification of 2×, and the afocal attachment may allow magnification of a received image at levels ranging from 2× to 4×. In this example, the entire telescope system with the afocal attachment installed will have an overall magnification of 4× to 8×. In another example, the magnification of the telescope can be increased, transforming a telescope with a 4× magnification into a telescope with a higher effective magnification. In some instances the afocal attachment's optical axis can be configured to permit independent adjustment, allowing for easy removal and reinstallation of the afocal attachment without a need to re-adjust the telescope itself.

A periscopic 12× zoom cell phone camera lens with eight million pixels comprises a first lens set arranged between an object side and an imaging surface, a second lens set arranged between the first lens set and the imaging surface, a third lens set arranged between the second lens set and the imaging surface, and an image sensor fixed at the imaging surface. The first lens set includes a prism, a first lens, and a second lens. The second lens set includes a third lens and a fourth lens. The third lens set includes a fifth lens. The light path is turned 90° due to the prism so that the length of the prism is equal to a thickness of the cell phone camera lens and the 60 mm length of the cell phone camera lens may be assembled in the cell phone to achieve 12× zoom.

A lens barrel includes: a first lens; a first tube that holds the first lens and moves along an optical axis; a focusing lens; an actuator that drives the focusing lens; and a second tube that holds the focusing lens and the actuator and moves along the optical axis.