Canon Kabushiki Kaisha

Yusuke Akiyama

Saburo Sugawara

A projection optical system including a plurality of positive lenses and a plurality of negative lenses is provided. Values for an Abbe number and anomalous dispersion of materials for a positive lens and a negative lens arranged in a predetermined range from an enlargement conjugate side and values for the Abbe number and the anomalous dispersion of materials for a positive lens and a negative lens arranged in a predetermined range from a reduction conjugate side are appropriately set.

Projection optical system and image projection apparatus including the same

A zoom lens includes a negative lens unit arranged closest to an enlargement conjugate side among lens units having negative refractive power included in the zoom lens, at least one positive lens unit having positive refractive power arranged closer to the enlargement conjugate side than the negative lens unit, and a rear lens unit including at least one lens unit and arranged closer to a reduction conjugate side than the negative lens unit, wherein a distance between adjacent lens units is changed during zooming, a stop is arranged closer to the reduction conjugate side than the negative lens unit, the rear lens unit includes at least one positive lens, and the positive lens satisfies a predetermined condition.

Zoom lens and projector using the same

A zoom lens includes, in order from an enlargement side to a reduction side, a first lens unit having positive refractive power and not moving for zooming, a second lens unit having negative refractive power and moving for zooming, a stop, a zooming lens unit having positive refractive power and moving for zooming, and a final lens unit having positive refractive power and not moving for zooming. During zooming from a wide-angle end to a telephoto end, the second lens unit moves to the reduction side and the zooming lens unit moves to the enlargement side. The zooming lens unit includes a cemented lens. The cemented lens includes a negative lens and a positive lens cemented in order from the enlargement side. A cemented surface of the cemented lens has a convex shape on the enlargement side. The zoom lens satisfies predetermined conditions.

Growing community of inventors

Utsunomiya, Japan

Yusuke Akiyama