Abstract: A high-performance, long-focal length macrolens system is provided which is easy-to-operate and is capable of photographing an object at an infinitely far distance and an object at a close distance without changing the overall length of the macrolens system. The system is configured in order from the object side, having:a first lens group G1, which includes a negative lens and has a positive overall refractive power,a second lens group G2, which includes a compound lens and has a negative overall refractive power,a third lens group G3, which includes a compound lens and has a negative overall refractive power, anda fourth lens group G4, which has a positive refractive power, and the system fulfills at least three preselected conditions.

Abstract: A long focal length microlens system that controls the variation of the aberration from the infinite object distance to shooting at equal magnification. The long focal length microlens system includes a first lens group G1 of positive refractive power a second lens group G2 of positive refractive power and a third lens group G3 of negative refractive power. When focusing from a infinite object distance to a close shooting distance, a value of D1 is reduced while a value of D2 is increased and a condition of 0.16<.vertline..DELTA.D1 .vertline./.DELTA.D2<0.5 is satisfied where D1 is a gap of lens apexes between said first group G1 and the second group G2. D2 is a gap of lens apexes between said second group G2 and the third group G3, .DELTA.D1 is (D1 at any object distance)-(D1 in the infinite object distance) and .DELTA.D2 is (D2 at any shooting distance)-(D2 in the infinite object distance).

Abstract: Macro telephoto lenses are disclosed for photographic use and that have a vibration compensation. The lenses have a relatively long focal length (as telephoto lenses), having a field of view of about 18.degree. or less and an F number of at least 4. Focusing is from infinity to a reproduction ratio of at least 1/2 and preferably 1/1 or more. The vibration compensation feature comprises at least one "antivibration lens element" in a lens group that is stationary in the direction of the optical axis. The antivibration lens element is operable to be transversely moved relative to the optical axis to counteract the effect of vibration and/or lens movement during photography. The lens preferably comprises a first positive lens group, a second positive lens group, a third negative lens group, and a fourth positive lens group.

Abstract: A telephoto lens system has a convergent forward group and a divergent rearward group. The forward group includes a first lens which is a biconvex lens having its surface of greater curvature facing the object side, a second lens which is a biconcave lens having its surface of greater curvature facing the object side, and a third lens which is a positive meniscus lens having its convex surface facing the object side. The rearward group includes a fourth lens which is a concave lens having its surface of greater curvature facing the object side, and a fifth lens which is a biconvex lens. The lens system satisfies predetermined conditions.

Abstract: A compact telephoto lens comprises, in succession from the object side, a first lens which is a single positive lens having its surface of sharper curvature facing the object side, a second lens which is a positive meniscus lens having its convex surface facing the object side, a third lens which is a single negative lens having its surface of sharper curvature facing the image side, a stop, and a fourth lens which is a single positive lens having its surface of sharper curvature facing the object side. The telephoto lens satisfies specific conditions.

Abstract: A viewfinder for a reflex camera for viewing the image formed through an objective lens comprises a reflecting member for reflecting a light flux from the objective lens in a predetermined direction, a transparent member for passing the reflected light therethrough, and a mat surface located at the exit side of the transparent member and convexly curved toward the entrance side of the transparent member. Thus, the image plane formed by the light flux passed from the objective lens through the transparent member is coincident with the mat surface convexly curved toward the entrance side.

Abstract: A modified Gauss type photographic lens system comprises, in the order from the object side, a first lens component which is a positive meniscus lens having its convex surface facing the object side, a second lens component which is a positive meniscus lens having its convex surface facing the object side, a third lens component which is a negative meniscus lens having its convex surface facing the object side, a fourth lens component which is a negative meniscus lens having its concave surface facing the object side, a fifth lens component which is a positive meniscus lens cemented to the fourth lens component and havings its convex surface facing the image side, and a sixth lens component which is a biconvex lens having its more curved surface facing the image side, the lens system satisfying certain conditions peculiar to the invention.

Abstract: The disclosure describes a compact and inexpensive optical system to be built in the viewfinder of a single-lens reflex camera for reading, in the viewfinder, an optical image of an indication element provided on the outside of the viewfinder. The optical system comprises a pentagonal Dach-prism having a light transmitting portion provided thereon, a first reflecting member and a second reflective member. The first and second reflective members have a specific positional relation to each other and also relative to the light transmitting portion of the prism so that an information carrying light beam coming from the indication element may reach the eyepiece of the viewfinder along a shortest possible light path.

Abstract: A wide angle photographic lens system comprises, in the order from the object side, a first lens component which is a positive lens having its more convex surface facing the object side, a second lens component which is a negative meniscus lens having its convex surface facing the object side, a third lens component which is a biconvex lens having its more convex surface facing the object side, a diaphragm, a fourth lens component which is a biconcave lens, a fifth lens component which is a positive meniscus lens having its convex surface facing the image side, and a sixth lens component which is a biconvex lens. Four distinctive optical conditions are characteristic of the lens system.

Abstract: A telephoto lens system having a relatively large aperture is composed of six lenses collected into four lens members, successively arranged, from the object side of the system to the image side, as follows: a first lens member including a positive lens whose convex surface faces the object side; a second lens member including a negative meniscus lens whose convex surface faces the object side and, a positive meniscus lens cemented to the negative meniscus lens; a third lens member including a positive lens whose convex surface faces the image side, and a biconcave lens cemented to the positive lens; and a fourth lens member consisting of a positive lens.The aberrations of the telephoto lens system of the invention are reduced even though the aperture is relatively larger than the apertures of prior art lens.