Abstract: A compact modified retrofocus-type wide-angle lens with a constant overall length during focusing is described, comprising, as seen from the object, a stationary front group (G1) with positive refractive power and a rear group (G2) with positive refractive power facing an image plane (IM), comprising an aperture stop (AP) arranged therebetween in a stationary manner, wherein the rear group (G2) consists of a first rear group portion (G2a) being displaceable along the optical axis and a second rear group portion (G2b) stationary in relation to the image plane (IM), wherein the first rear group portion (G2a) and the second rear group portion (G2b) have positive refractive power and the distance between the first rear group portion (G2a) and the front group (G1) reduces during focusing from infinity to close range.

Abstract: What is described is a modified retrofocus-type wide-angle lens, with, as seen from the object, a front group (G1) with negative refractive power, a first rear group (Gh1) with positive refractive power displaceable along the optical axis for focusing purposes and a second rear group (Gh2) with positive refractive power facing an image plane.

Abstract: What is described is a modified retrofocus-type wide-angle lens, with, as seen from the object, a front group (G1) with negative refractive power, a first rear group (Gh1) with positive refractive power displaceable along the optical axis for focusing purposes and a second rear group (Gh2) with positive refractive power facing an image plane.

Abstract: An angular attachment has a housing (1) for fixing to an eyepiece (15) of a rangefinder camera (21) with laterally correct and height-correct representation of the finder image at an altered eyepiece angle, which contains a Bauernfeind prism (5) with double reflection in one plane as an image deflection element, a first region (A, A?) of a base area (4) of the Bauernfeind prism (5) is disposed downstream of the eyepiece finder (15), an area opposite to this region is formed as a reflective area (8) and is inclined with respect to the base area (4) in such a way that a ray (2) entering the first region perpendicularly is reflected onto a second region (B, B?) of the base area (4) at an angle of total reflection, and a light exit area (10) of the Bauernfeind prism (5) is inclined relative to the base area (4) in such a way that the totally reflected ray (9) impinges perpendicularly on the light exit area (10).

Abstract: A photographic objective of the modified double gauss type is presented. The object has a forward group that includes three lens elements (L1, L2, L3) and has the refractive power sequence ++?. The objective also includes an aperture and a rear group including lens elements (L4, L5, L6) of refractive power sequence ?++. The lens element of negative refractive power (L4) is designed as a meniscus with an aspheric surface concave relative to the aperture, and a lens element of negative refractive power (L7) with surfaces concave on both sides is arranged downstream of the last lens element of positive refractive power (L6).

Abstract: A description is given of a photographic objective of the modified double gauss type having a front group, comprising of three lens elements (L1, L2, L3) and having the refractive power sequence ++?, an aperture and a rear group including lens elements (L4, L5, L6) of refractive power sequence ?++, which is distinguished in that in the rear group the lens element of negative refractive power (L4) is designed as a meniscus with an aspheric surface concave relative to the aperture, and a lens element of negative refractive power (L7) with surfaces concave on both sides is arranged downstream of the last lens element of positive refractive power (L6).

Abstract: An optical lens arrangement for a rangefinder system in a photographic camera with a fixed viewfinder magnification SK and a fixed measuring base MB is configured to be coupled with a rangefinder eyepiece of the rangefinder system and is designed as an afocal telescope with a minimum 1.1 times and a maximum 1.7 times magnification SL. The magnification SL may be selected so that the product of the viewfinder magnification SK and the magnification SL is at least very nearly equal to 1.

Abstract: An optical lens arrangement for a rangefinder system in a photographic camera with a fixed viewfinder magnification SK and a fixed measuring base MB is configured to be coupled with a rangefinder eyepiece of the rangefinder system and is designed as an afocal telescope with a minimum 1.1 times and a maximum 1.7 times magnification SL. The magnification SL may be selected so that the product of the viewfinder magnification SK and the magnification SL is at least very nearly equal to 1.

Abstract: A lens testing device comprises a holder, fitted on a stand, for mounting a lens specimen, a test object illuminated from the rear, an imaging objective and a detector for evaluating the image of the test object. The imaging objective can be combined with the detector to form a unit. The lens specimen is an objective specimen and the test object is arranged in the focal plane of the objective specimen inside the holder. The imaging objective is a collimator objective and the detector is arranged in the focal plane of the collimator objective. Either the holder or the unit is pivotably supported on the stand and the holder and the unit can be pivoted relative to one another.

Abstract: The invention provides a switchable bright-field transmitted-light illumination device for microscopes which provides for in each case two objectives of different apertures in both switch positions a simple automatic illumination arrangement without adjustment of the position and of the opening of the diaphragms. For this purpose, in an illumination device, comprising light source 1, collector 2, field diaphragm 3, aperture diaphragm 4 and basic condenser 7 with removable condenser head 8 or condenser lens element 11, which can be switched in alternatively to the condenser head 8 between the aperture diaphragm 4 and the basic condenser 7, the aperture diaphragm 4 is arranged between the collector 2 and the field diaphragm 3 and is imaged by an intermediate imaging by at least two auxiliary lenses 5 and 6 into a plane 12 conjugate with the aperture diaphragm 4.