Means and method for calibrating light responsive exposure control system

Exposure control apparatus together with support means for admitting a select amount of light corresponding to a select film speed during a photographic exposure interval wherein the exposure control apparatus may be utilized with a camera of the type having a housing and an objective lens mounted on the housing and defining a film plane, said exposure control apparatus and support means comprising:

• a wall member;
• means for detecting scene light incident thereon and for providing an output response;
• a wall member;
• means for detecting scene light incident thereon and for providing an output response;
• a blade assembly movable along a predetermined path between a first position wherein it precludes scene light from reaching the film plane and light detecting means and a second position wherein it defines at least one maximum sized aperture which permits a maximum amount of scene light to impinge upon the film plane and light detecting means, said blade assembly serving to define at least one range of progressively increasing sized apertures as it moves from said first position toward said second position upon the commencement of an exposure interval;
• selectively actuable means for moving said blade assembly between said first and second positions;
• control circuit means for actuating said moving means into moving said blade assembly toward said first position to terminate an exposure interval as a result of the time integration of said output response from said light detecting means reaching a select value;
• a light attenuating filter;
• means for movably connecting said light attenuating filter with respect to said wall member thereby facilitating the positioning of said light attenuating filter in intercepting relation with a select portion of the scene light directed toward said light detecting means, said select intercepted portion of the scene light being determined during the manufacture of said exposure control system to provide the requisite output response from the light detecting means for the control circuit to actuate said scene light varying means to terminate an exposure interval in time to insure that the amount of scene light incident to the film plane substantially corresponds to the select film speed;
• and
• means for permanently fixing the position of said light attenuating filter in immovable relation with respect to said wall member subsequent to the determination of said select intercepted portion of the scene light.

A method for calibrating an exposure control system to provide a select amount of light corresponding to a select film speed during a photograhic cycle for a camera of the type including:

• a housing, an objective lens mounted on the housing, means for defining a film plane within the housing, means for detecting light, selectively actuable means for varying the amount of scene light incident on the film plane and light detecting means during an exposure cycle, control circuit means responsive to the light detecting means for selectively actuating the scene light varying means to terminate an exposure cycle, and a light attenuating calibration filter selectively movable into scene light intercepting relation with respect to the scene light directed toward the light detecting means;
• said method comprising the steps of:
• providing a light source of select illuminationg to illuminate the film plane and light detecting means as a function of the scene light varying means operation during an exposure cycle;
• actuating the scene light varying means into an exposure cycle to allow light from the light source to impinge upon the film plane and light detecting means whereupon the control circuit means thereafter actuates the scene light varying means to terminate the exposure cycle as a function of the exposure time and light intensity incident upon the light detecting means;
• measuring the light intensity upon the film plane during the exposure cycle;
• integrating the measured light intensity at the film plane during the exposure cycle to provide an exposure value;
• correlating said exposure value to the speed of a select film;
• and
• moving said calibration filter to alter the portion of scene light intercepted by said filter if the exposure value does not correlate to the speed of the select film and then repeating the steps of said calibrating method until said exposure value correlates to the speed of the select film.