Abstract: In an objective lens assembly for an optical instrument comprising inner and outer tube members with outer and inner engaged helicoidal screws, respectively, the normal trapezoidal-section main ridge of the helicoidal screw of the outer tube member is modified to provide one or more wall surfaces that reflect stray light from the object side of the objective lens assembly to prevent such light from reaching the image side of the assembly. The wall surface or surfaces are provided by one or more sub-ridges or grooves at the top of the trapezoidal-section main ridge. Bottom portions between successive elements of the main ridge may be angulated to prevent stray light reflected therefrom from reaching the image end of the assembly.

Abstract: A camera is capable of displacing a phototaking optical system in the direction of the optical axis by a drive source such as motor and setting the optical system to a plurality of positions.

Abstract: A camera containing a lens barrier therein is comprised of a helicoid rotatable about the optic axis, a rectilinear barrel threadably engaged with the inner side of the helicoid and having a holding portion for a lens barrier holding a photo-taking lens and protecting the photo-taking lens, a guide plate extending in the direction of the optic axis and engaged with the rectilinear barrel to rectilinearly guide the same through a cut-away groove, and a lens barrier held in the lens barrier holding portion and opened and closed in front of the photo-taking lens. The guide plate and the lens barriers are designed so as to be capable of overlapping each other in the direction of the optic axis, and the guide plate is designed so as not to hamper the opening-closing of the lens barriers even when they are in the overlapping position.

Abstract: Variable focus camera includes primary and secondary lens systems, in which only the primary lens system is used for wide angle shots while the combination of the primary with the secondary lens system is used for telephoto shots.The variable focus camera can exactly and positively control the focus change region, the automatic focusing region and other regions.

Abstract: The present invention relates to a camera in which photographing lens means is moved along an optical axis thereof between an extended position and a withdrawn position, a lens system of the lens means being protected by protective cover means moved by cover operating means, and being moved by lens operating means, motion of the protecting cover means and the lens system being controlled by control means.

Abstract: A device for positioning a photographing lens to focus the lens on an object is disclosed. The device comprises distance detecting means for detecting a distance to an object to provide an output signal, the distance detector detecting the distance when the object is positioned in the range of ordinary photographing distances and in the range of distances shorter than the ordinary photographing distances, a position determining system for determining the position of the photographing lens in the direction of the optical axis according to the output signal, and a drive system for responding to an output of the position determining system. The drive system includes a cam which is displaced to move the photographing lens along the optical axis.