Abstract: In this invention, to provide a compact zoom lens having a small number of optical element groups to be driven and a simple moving mechanism, at least one of a plurality of optical element groups arranged in the lens system includes a refractive power variable element of a transmission type which has a compensation function to correct focus movement caused by zooming and a focus function to correct focus movement caused by a variation in inter-object distance. The refractive power variable element is a liquid optical element including a first liquid having a conductivity or a polarity and a second liquid which is not mixed with the first liquid, the first liquid and the second liquid being enclosed in a container fluid-tight so as to define an interface therebetween having a predetermined shape, the liquid optical element being arranged such that a refractive power thereof is adjusted by changing a curvature of the interface.

Abstract: A zoom lens includes: a first lens group with a positive refractive power; a second lens group with a negative refractive power; a third lens group with a positive refractive power; a fourth lens group with a positive refractive power, which are arranged in this order from an object side of the zoom lens. The first lens group and the third lens group are positioned statically. The second lens group is moved for zooming the zoom lens. The fourth lens group is moved for correcting a focus movement caused by the zooming and is further moved for focusing the zoom lens. The second lens group is provided with: a negative lens in a meniscus shape; a negative lens; a positive lens; and a negative lens, which are arranged in this order from an objective side of the zoom lens.

Abstract: A zoom lens includes: a first lens group with a positive refractive power; a second lens group with a negative refractive power; a third lens group with a positive refractive power; a fourth lens group with a positive refractive power, which are arranged in this order from an object side of the zoom lens. The first lens group and the third lens group are positioned statically. The second lens group is moved for zooming the zoom lens. The fourth lens group is moved for correcting a focus movement caused by the zooming and is further moved for focusing the zoom lens. The second lens group is provided with: a negative lens in a meniscus shape; a negative lens; a positive lens; and a negative lens, which are arranged in this order from an objective side of the zoom lens.

Abstract: In this invention, to provide a compact zoom lens having a small number of optical element groups to be driven and a simple moving mechanism, at least one of a plurality of optical element groups arranged in the lens system includes a refractive power variable element of a transmission type which has a compensation function to correct focus movement caused by zooming and a focus function to correct focus movement caused by a variation in inter-object distance. The refractive power variable element is a liquid optical element including a first liquid having a conductivity or a polarity and a second liquid which is not mixed with the first liquid, the first liquid and the second liquid being enclosed in a container fluid-tight so as to define an interface therebetween having a predetermined shape, the liquid optical element being arranged such that a refractive power thereof is adjusted by changing a curvature of the interface.

Abstract: An image pickup apparatus comprises a substrate; an image pickup element to convert a converged light flux to electronic signals; an image-taking optical element positioned so as to converge a light flux from an object onto the image pickup element; a light shielding member to house the image pickup element and the image-taking optical element; a controlling device to control an output of the electronic signals and controlling the image pickup element; and a refracting power-variable optical element.

Abstract: An image pickup apparatus comprises a substrate; an image pickup element to convert a converged light flux to electronic signals; an image-taking optical element positioned so as to converge a light flux from an object onto the image pickup element; a light shielding member to house the image pickup element and the image-taking optical element; a controlling device to control an output of the electronic signals and controlling the image pickup element; and a refracting power-variable optical element.