Abstract: A telephoto lens system comprising a front lens group of a positive refractive power fixed on the optical axis and a rear lens group of a negative refractive power is provided. The rear lens group consists, from the object to the image side, of a first positive subunit fixed on the optical axis, a second negative subunit movable along the optical axis and a third positive subunit fixed on the optical axis, the second negative subunit being movable toward the image side for focusing to a closer object. The object side end surface of the first positive subunit is concave and fulfills the following condition in relation with the front lens group:0.6<.vertline..phi.'.sub.II-1 .vertline./.phi..sub.I <2.

Abstract: A catadioptric light system such as a module lens system capable of being mounted on a camera is provided. A plurality of light reflecting and refracting optic members are designed to provide a desired image forming light path through the lens system. Disposed within the lens system is an electrochromic device that is responsive to an applied voltage to provide a predetermined degree of light transmission intensity through the lens system. The electrochromic device can be a thin film mounted on a transparent plate or on a reflective surface. The housing of the lens system can be advantageously designed to contain its own power source.

Abstract: A projection television system having a light emitting target and a screen for realizing a projected video image is provided with an improved reflecting optical system which provides enhanced resolution and uniform correction of aberrations across a projected image. The optical system includes a concave mirror, positioned adjacent the light emitting target, for reflecting the video image towards the display screen. An optical compensating plate having at least one aspherical surface is located on the optical path. A meniscus lens is also located in the optical path. Both the optical compensating member and the meniscus lens can be positioned outside the vacuum envelope of the target and the electron gun to simplify alignment and construction.

Abstract: An electrochromic light regulator for adjusting or regulating the amount of light passing therethrough comprises first, second and third electrode units stacked one above the other in spaced manner. A space between each adjacent two of the first to third transparent electrode units contains an electrochromic material and an ion conducting and electrically insulating layer. The second transparent electrode unit which is positioned intermediately between the first and third transparent electrode units serves as a counter electrode common to the first and third transparent electrode means.

Abstract: The present lens system is capable of providing both a zooming operation and also a relatively efficient and economical macrophotography mode of operation. The zoom lens system contains the basic conventional lens groups of a focusing lens group, variator lens group, compensator lens group and relay lens group. These individual lens group function in a conventional manner during a zooming mode of operation. However, during the macrophotography mode of operation, the individual lens element that form the relay lens group are capable of coordinate movement with other lens elements in the lens system to provide a relatively compact and economical lens design for macrophotography.

Abstract: A constant magnification zoom lens system is provided that has the capability of permitting a predetermined desired constant magnification of an image during a zoom operation. A variator lens group for varying the focal length of the lens system and a compensator lens group for controlling the position of an image formed by the lens system is provided. Pairs of cam and follower assemblies can be provided in the barrel mechanism to control the movement of the respective compensator lens group and variator lens group so that the position of an image of a fixed object is maintained within a predetermined depth of focus in a normal zooming mode of operation and also the position of an image of a moving object can be maintained within a predetermined depth of focus in response to any variation of focal length to provide a constant magnification photography mode.

Abstract: An aperture stop control device for a zoom lens system includes a variable aperture stop, a first sensor for determining the diameter of the aperture stop and providing a first electrical signal representative of the diameter of the aperture stop means and a second sensor for generating a second electrical signal indicative of a designated F number. A signal generator provides a third electrical signal indicative of the focal length of the zoom lens system. A computing circuit computes an output electrical signal as a function of the second and third electrical signals to control the diameter of the aperture stop for automatically maintaining a designated F number during a zooming operation.

Abstract: An objective lens system particularly adapted for photography with a frontal aperture stop is provided. The lens system includes four lens components including a positive doublet. A diaphragm is provided in front of the first lens component and the lens system satisfies the following relationships;1.84 > N.sub.1 > 1.6 (1) 65 > V.sub.1 > 44 (2)0.7 > d.sub.1 + d.sub.2 /.SIGMA.d > 0.3 (3) 1.5 > .vertline.R.sub.3 .vertline./R.sub.4 > 0.5 (4)0.25 > .vertline.n.sub.3 - n.sub.4 .vertline. > 0.03 (5) 25 > .vertline.V.sub.3 - V.sub.4 .vertline. > 5 (6)0.0005 > n.sub.4 - n.sub.3 /r.sub.6 < 0.0035 (7) 1.0 > R.sub.5 /R.sub.7 > 3.0 (8)wherein, N, is the index of refraction, V is the Abbe number, D are axial distances along the optical axis and R is the radii of curvature. The subnumbers refer to consecutive measurements along the optical axis.

Abstract: The present lens system is capable of providing not only a zooming function over a relatively wide range, but also macrophotography. The zoom lens system includes a first lens group capable of varying the focal length without a loss of focus and a second lens group forming a master lens group. The second lens group is spatially displaced on the image side of the first lens group and includes a lens component movably mounted on the optical axis of the system that is capable of varying the focal length of the second lens group. The movable lens component in the second lens group has two positions which will provide the same final image plane for the entire zoom lens system, for example, a forward and backward position does not introduce any image plane deviations and permits an extension of the zoom range of the total lens system. The intermediate position of the movable lens component of the second lens group can be utilized for focusing in a macrophotography range.

Abstract: A compact varifocal lens system, such as a zoom lens assembly, is provided having a front focusing lens component of negative refractive power, a variator lens component of positive refractive power, a compensator lens component of negative refractive power and a master lens component. The lens assembly has a compact configuration and further, provides a highly desirable macrophotography capability. The macrophotography mode of operation can be effected by fixing one of the variator and compensator lens components, or by separating one of the variator and compensator lens components into positive and negative subcomponents with a predetermined relative positioning of the subcomponents to provide a close-up focusing.

Abstract: A macro-photography varifocal lens assembly is provided for attachment to a camera body. The lens assembly can include a first lens group of negative refractive power and a second lens group of positive refractive power further supplemented by a master or auxiliary lens group of positive refractive power. One of the first and second lens groups are mounted for relative movement to vary the overall focal length of the lens assembly as the lens group moves across a predetermined range of movement. The image plane of the refracted image is continuously shifted from an initial predetermined position at one end of the range of movement towards the object and then away from the object to return to the initial predetermined position at the other end of the range of movement. This relative movement or shift of the image plane towards the object being sufficient to focus an image of an object in a macro-photography range.