A zoom taking lens for a photographic single lens reflex (SLR) camera. The lens has an air space between elements of the lens, which air space is large enough to accommodate reflective means for directing rays which have passed through elements of the lens in front of the reflective means, to viewfinder means. By being able to accommodate the reflective means within the length of the lens and with the reflective means being axially movable the back focal length of the lens may be much smaller than is the case in a conventional SLR camera in which the reflective means is movable into and out of the back focal length between the rearmost element of the lens and the film of the camera.
An object is to provide a zoom lens system having compactness of about a normal lens, small number of lens elements, a zoom ratio about 2.9, good productivity, and high optical performance. The system includes, in order from the object, a first lens group with negative power and a second lens group with positive power. Zooming is performed by varying a distance between the first lens group and the second lens group. The first lens group includes at least a negative lens and a positive lens. The second lens group includes a front lens group with positive power and a rear lens group with positive power. The front lens group includes a positive lens and a cemented lens constructed by a positive lens cemented with a negative lens. The rear lens group includes a cemented lens constructed by a negative lens cemented with a positive lens. Given conditions are satisfied.
In a zoom lens having a high variable magnification, first and second lens groups and respectively having negative and positive focal lengths are sequentially arranged from an object side of the zoom lens to an image side thereof. A combined focal length of an entire lens system is charged by changing a distance between the first and second lens groups while the position of an image surface is constantly held. The zoom lens is constructed such that the second lens group is constructed by front and rear lens groups respectively having positive and negative focal lengths.
This invention relates to a zoom lens system that is an object lens for taking images which is independent of an objective lens for a viewfinder, said zoom lens system being less likely to vary in the total length by zooming in spite of having a high zoom ratio and being reduced in the total length under every condition from the wide angle to telephoto settings. To achieve this, the present zoom lens system is made up of a first lens unit having a negative refractive power, a second lens unit having a positive refractive power and a third lens unit having a positive refractive power. In zooming from the wide angle to telephoto end the spaces between the respective lens units are variable, and the present lens system satisfies the following condition: where f.sub.B is the back focus of the total system and h is the maximum image height of an image to be taken.
A finite conjugate distance zoom lens system includes sequentially from the enlarging side a first lens group having a negative refracting power and a second lens group having a positive refracting power. The second lens group consists of sequentially from the enlarging side two or three positive lens elements, first and second cemented lenses, a negative lens element, and a positive lens element. Both of the first and second lenses consist of cemented biconvex lens element and negative lens element. During a zooming operation from the maximum focal length edge to the minimum focal length edge, the first lens group shifts from the enlarging side to the reducing side on the maximum focal length side and shifts from the reducing side to the enlarging side on the minimum focal length side. On the other hand, the second lens group monotonously shifts from the enlarging side to the reducing side during the zooming operation.
The invention provides a compact zoom lens system which has an angular coverage from wide angle to moderate telephoto and makes a relatively bright and parallax-free TTL finder possible and in which a first unit 11 having a positive power as a whole is located on the side proximate to the object. The lens system includes a reflective means 13c located more closely to the image side than the first unit 11 for guiding incident light to a finder subsystem and a movable lens unit that moves for zooming. The movable lens unit comprises a sub-unit 13a having a positive power as a whole and located on the object side of the reflective means 13c and a sub-unit 13b having a negative power as a whole and located on the images side of the reflective means 13c, or alternatively a sub-unit having a negative power as a whole and located on the object side of the reflective means and a sub-unit having a positive power as a whole and located on the image side of the reflective means. The movable lens unit has an aperture stop located therein or adjacent thereto.
