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.

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 lens apparatus includes a lens unit including a first lens, a fixing frame which holds the lens unit with the lens unit being movable in a direction of an optical axis of the lens unit, and a first power transmission device configured to transmit power to the lens unit. The lens unit includes a balancer and a second power transmission device. The balancer and the second power transmission device are configured such that a force applied to the balancer causes the second power transmission device to reduce a load applied to the first power transmission device in a case where the lens unit is moved in a direction against a gravitational force applied thereto.

The invention relates to a microscope (10) that encompasses an objective system (30) having at least two objectives (44, 52) selectably introducible into the beam path of the microscope (10), and a zoom system (32). The zoom system (32) has a total zoom range (90) within which the focal length of the zoom system (32) is settable. A zoom sub-range (96, 98) within the total zoom range (90) is allocated to each of the objectives (44, 52).

An embodiment provides an imaging lens comprising first to third lens groups arranged sequentially from an object side to an image side and having refractive power, wherein the distances of the second lens group and the third lens group from the first lens group are variable such that a tele mode having a narrow angle of view and a wide mode having a wide angle of view can be implemented, the EFL in the tele mode is no more than 2.5 times the EFL in the wide mode, 2<F.sub.number<5 and 15 mm<TTL40 mm.

An imaging lens comprises in order from an object, a first lens group of positive refractive power, a second lens group of positive refractive power, and a third lens group of negative refractive power. In focusing from infinity to a close object, the first lens group is fixed in position, and the second lens group and the third lens group are moved so that the distance between the first lens group and the second lens group is reduced, and the distance between the second lens group and the third lens group is increased. Further, the following conditional expression (1) is satisfied:

1.0<f1/f<2.5(1) where f1: is the focal length of the first lens group, and f: the focal length of the entire system.

An image processing apparatus includes: a memory configured to acquire a plurality of visual point images; a visual point change processing unit configured to perform image processing on image data based on the plurality of visual point images to generate a combination image; an area designation unit configured to designate an area subjected to the image processing using the visual point change processing unit; and an adjustment unit configured to set an adjustable range of the image processing for each area designated by the area designation unit.

The effective focal length of an optical system can be electronically controlled using switchable wave plates in conjunction with polarized light.

An imaging lens includes a first lens group, a second lens group having positive refractive power, an aperture, and a third lens group having positive refractive power, sequentially disposed in that order from an object side to an image side. During a focusing from infinity to a short length, a combination of the second lens group, the aperture, and the third lens group as a single unit moves to the object side so as to reduce a distance to the first lens group. The second lens group includes four lenses of a second-first negative lens, a second-second positive lens, a second-third negative lens, and a second-fourth positive lens sequentially disposed in that order from the object side to the image side.

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.