Abstract: A selective permeable membrane having self-supporting property which comprises a polyimide polymer consisting essentially of a repeating unit of the formula: ##STR1## wherein R is a divalent organic group, and a process for preparing the same.

Abstract: A rangefinder mechanism is shown in which the scanning mirror has been replaced with a movable scanning optic. The automatic rangefinder system includes a pair of optical paths, one a reference path and the other a scanned path, which are lead to impinge upon a photosensitive surface for comparison purposes. The output of the photosensitive surface is used to adjust the main lens of the camera. The range of the movable optic is coordinated with the position of the main lens of the camera as feedback and adjustment of the rangefinder.

Abstract: An automatic rangefinding optical system for a camera includes optics conted for movement subject to the operative zooming main lens. The rangefinding system has an automatic focusing device which generates a pulse when separate objective images from two optical system paths coincide. Zooming the rangefinder along the two optical system paths gives more precise automatic focusing of the subject by optically modifying the objective images according to the zoom position of the main lens.

Abstract: A rangefinder mechanism is shown in which the scanning mirror has been reced with a movable scanning optic. The automatic rangefinder system includes a pair of optical paths one a reference path and the other a scanned path which are led to impinge upon a photosensitive surface for comparison purposes. The output of the photosensitive surface is used to adjust the main lens of the camera. Disposed in front of the movable optic is another optical movable relative thereto to coordinate with the position of the main lens of the camera as feedback and adjust the rangefinder system.

Abstract: A continuous electrolytic treatment apparatus for anodic oxidation and electrolytic coloring operations on an object such as a strip, wire or foil of aluminum and its alloys, wherein there are provided electric field buffer means which comprises a plurality of self-standing plates of plastic resin or the like having an electrically insulating property. The electric field buffer means are located at least in one zone in the electrolytic cell so that it can serves to effectively buffer concentration of excessive electric current to the interface between the object and the electrolytic solution at the above mentioned zone, thereby preventing burning in the surface of the object or in the oxide film formed thereon during the anodic oxidation treatment and unevenness in coloring of the object during the electrolytic coloring operation due to such current concentration, particularly when treating with a high current density.