Abstract: Disclosed is a zoom lens system including in an order from an object side to an image side: 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 which zooming is performed by changing each distance among the first, second, and third lens units. In this zoom lens system, partial charge of a changing magnification between the second and third lens units is suitably set to maintain excellent optical performance over the overall zoom area while a zoom ratio is large.

Abstract: A zoom lens system including, in order from an object side to an image side, a first lens unit of positive optical power, and a second lens unit of negative optical power, followed by a lens component having a lens unit, wherein at least one of the first lens unit and the second lens unit moves during zooming. One of the lens units of the zoom lens system includes a layer made of a material that satisfies the following conditions: 11<?IT<27 0.2<?IT<0.4. Wherein ?IT is an Abbe number of the layer, and ?IT is a partial dispersion ratio for the g-spectral line and f-spectral line of the layer. The layer has an optical power of a sign opposite to that of the lens unit including the layer.

Abstract: A zoom lens of a novel configuration suitable for a collapsible lens barrel is disclosed. More specifically, here is disclosed a zoom lens, comprising four lens units which are, in the order from an object side toward an image side, positive, negative, positive and positive in optical power, and performing zooming by varying distances between each lens units. In this zoom lens, the fourth lens unit has a positive lens element and a negative lens element, and satisfies the following conditional expression: ?n??p where ?n is the Abbe number of the negative lens element of the fourth lens unit, and ?p is the Abbe number of the positive lens element of the fourth lens unit.

Abstract: A reflecting-type optical system according to the invention includes an optical element composed of a transparent body having an entrance surface, an exit surface and at least three curved reflecting surfaces of internal reflection. A light beam coming from an object and entering at the entrance surface is reflected from at least one of the reflecting surfaces to form a primary image within the optical element and is, then, made to exit from the exit surface through the remaining reflecting surfaces to form an object image on a predetermined plane. In the optical system, 70% or more of the length of a reference axis in the optical element lies in one plane.

Abstract: A zoom lens comprising four lens units is disclosed which achieves a high variable magnification ratio and favorable optical performance at an arbitrary zoom position. The zoom lens of the present invention includes, in order from an object side, a first lens unit having positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. During zooming from the wide angle end to the telephoto end, the spacing between the first and second lens units is increased, the spacing between the second and third lens units is decreased, the spacing between the third and fourth lens units is increased, and an aperture stop moves together with the third lens unit. In addition, specific conditions are satisfied.

Abstract: In an image pickup apparatus which permits switching between a moving-image shooting mode and a still image shooting mode and is provided with an automatic focusing device for focus adjustment by detecting a high frequency component of a video signal to use it as a focus evaluating signal, the focusing action of the automatic focusing device is arranged to be restarted when the moving-image shooting mode is switched to the still-image shooting mode.

Abstract: A zoom lens system comprises a 1st lens unit with positive optical power consisting of one lens element, a 2nd lens unit with negative optical power, a 3rd lens unit with positive optical power and a 4th lens unit with positive optical power, in order from the object side to the image side is disclosed. During zooming, the 1st lens unit and 3rd lens unit move so as to be located closer to the object side at the telephoto end than at the wide-angle end. Then, by appropriately setting the amount of movements of the 1st lens unit, 2nd lens unit and 3rd lens unit during zooming, the overall length of the zoom lens system is reduced and excellent optical performance is realized.

Abstract: A zoom lens comprising four lens units is disclosed which achieves a high variable magnification ratio and favorable optical performance at an arbitrary zoom position. The zoom lens of the present invention includes, in order from an object side, a first lent unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. During zooming from the wide angle end to the telephoto end, the spacing between the first and second lens units is increased, the spacing between the second and third lens units is decreased, the spacing between the third and fourth lens units is increased, and an aperture stop moves together with the third lens unit. In addition, specific conditions are satisfied.

Abstract: A reflecting type of zoom optical system comprises a plurality of optical elements each of which includes a transparent body and two refracting surfaces and a plurality of reflecting surfaces formed on the transparent body and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection by the plurality of reflecting surfaces, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from surface reflecting mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: A reflecting type of zoom optical system comprises a plurality of optical elements each of which includes a transparent body and two refracting surfaces and a plurality of reflecting surfaces formed on the transparent body and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection by the plurality of reflecting surfaces, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from surface reflecting mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: A zoom lens which has good optical performance with the number of lenses reduced as a result of forming a diffraction optical surface is disclosed. The zoom lens includes, in order from object side to image side, a first lens unit consisting of a positive lens element and having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. When zooming is performed from a wide angle end to a telephoto end, the first lens unit and the third lens unit are moved so that, at the telephoto end, they are closer to the object side, and the second lens unit is moved so that, at the telephoto end, it is closer to the image side. The zoom lens further includes at least one diffraction optical surface.

Abstract: An optical element of a transparent body has two refracting surfaces formed in surfaces of the transparent body, and a plurality of reflecting surfaces formed in surfaces of the transparent body. Light incident through one refracting surface into the transparent body is reflected successively by the plurality of reflecting surfaces to be guided to the other refracting surface. At least one of the two refracting surfaces and reflecting surfaces has an optical low pass filter.

Abstract: A zoom lens of a novel configuration suitable for a collapsible lens barrel is disclosed.

Abstract: When n is taken as integers of 2 or more, n reflecting systems are constituted by providing reflecting mirrors on opposite (two) side surfaces in 2n side surfaces of a transparent body having the shape of a 2n-sided prism. The n reflecting systems are provided on each pair of opposite side surfaces, and images of an object are formed using each of the n reflecting systems.

Abstract: An optical element of a transparent body has two refracting surfaces formed in surfaces of the transparent body, and a plurality of reflecting surfaces formed in surfaces of the transparent body. Light incident through one refracting surface into the transparent body is reflected successively by the plurality of reflecting surfaces to be guided to the other refracting surface. At least one of the two refracting surfaces and reflecting surfaces has an optical low pass filter.

Abstract: A reflecting type of zoom optical system comprises a plurality of optical elements each of which includes a transparent body and two refracting surfaces and a plurality of reflecting surfaces formed on the transparent body and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection by the plurality of reflecting surfaces, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from surface reflecting mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: An optical system of reflecting type according to the invention comprises an optical element composed of a transparent body having an entrance surface, an exit surface and at least three curved reflecting surfaces of internal reflection, wherein a light beam coming from an object and entering at the entrance surface is reflected from at least one of the reflecting surfaces to form a primary image within the optical element and is, then, made to exit from the exit surface through the remaining reflecting surfaces to form an object image on a predetermined plane, and wherein 70% or more of the length of a reference axis in the optical element lies in one plane.

Abstract: A disclosed optical apparatus comprises an optical unit including a light entrance surface, light reflecting surfaces and a light exit surface all of which are integrally formed of transparent material, and the optical unit has in its interior an internal refracting surface for refracting light. Since a light beam passes through the optical unit from the light entrance surface to the light exit surface via the internal refracting surface and the light reflecting surfaces along a bent optical path, the optical apparatus is reduced in size and improved in optical performance, particularly, well corrected in chromatic aberration. Another disclosed optical apparatus is arranged to achieve zooming by using a plurality of optical units each of which is similar to the aforesaid optical unit.

Abstract: A zoom lens which has good optical performance with the number of lenses used reduced as a result of forming a diffraction optical surface is disclosed. More specifically, there is disclosed a zoom lens that includes, in order of lens units from an object side to an image side, a first lens unit consisting of a positive lens element and having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. When zooming is performed from a wide angle end to a telephoto end, the first lens unit and the third lens unit are moved so that, at the telephoto end, they are positioned closer to the object side than to the wide angle end, and the second lens unit is moved so that, at the telephoto end, it is positioned closer to the image side than to the wide angle end. The zoom lens further includes at least one diffraction optical surface.

Abstract: A reflecting-type optical system according to the invention includes an optical element composed of a transparent body having an entrance surface, an exit surface and at least three curved reflecting surfaces of internal reflection. A light beam coming from an object and entering at the entrance surface is reflected from at least one of the reflecting surfaces to form a primary image within the optical element and is, then, made to exit from the exit surface through the remaining reflecting surfaces to form an object image on a predetermined plane. In the optical system, 70% or more of the length of a reference axis in the optical element lies in one plane.