Abstract: Disclosed herewith is a rear projection optical system for being installed at a rear side of a screen of a rear projection apparatus. The rear projection system comprises: a display panel; a illuminating optical system for illuminating the display panel, the illuminating optical system being decentered from a screen center in both of a horizontal direction and a vertical direction; and a projection optical system, decentered from the screen center in the vertical direction, for projecting a display image on the display panel projected by the illuminating optical system onto a screen through a rear mirror positioned at a position that is the center of the screen. The projection optical system comprises a dioptric system, a deflection mirror, and a curved mirror in this order from the display panel to the rear mirror, and the curved mirror is decentered from the screen center in the vertical direction but centered against the screen center in the horizontal direction.

Abstract: Disclosed herewith is a rear projection optical system for being installed at a rear side of a screen of a rear projection apparatus. The rear projection system comprises: a display panel; a illuminating optical system for illuminating the display panel, the illuminating optical system being decentered from a screen center in both of a horizontal direction and a vertical direction; and a projection optical system, decentered from the screen center in the vertical direction, for projecting a display image on the display panel projected by the illuminating optical system onto a screen through a rear mirror positioned at a position that is the center of the screen. The projection optical system comprises a dioptric system, a deflection mirror, and a curved mirror in this order from the display panel to the rear mirror, and the curved mirror is decentered from the screen center in the vertical direction but centered against the screen center in the horizontal direction.

Abstract: A zoom lens barrel having a macro-photographing mechanism including a main barrel carrying a control ring assembly which is divided into a first operating ring rotatable and slidable relative to the main barrel along the optical axis thereof, and a second operating ring movable with the first operating ring along the optical axis, the second operating ring being rotatable about the optical axis relative to the first operating ring. The rotation of the first operating ring effects the focusing of a lens system for ordinary photography, and the slide movement of the first operating ring effects zooming by causing a cam ring integral with the second operating ring to follow said movement, whereby when the cam ring is positioned at the wide-angle end or the telephoto end in zooming, the cam ring effects focusing of the lens system for macro-photography due to the rotation of the second operating ring relative to the first operating ring.