Sensitometric Aspect of Television Monitor-Tube Photography

The performances of the iconoscope and orthicon pickup tubes and kinescope monitor tubes constituting a television system are considered in regard to the response versus level characteristics. A nonlinear electrical network is advocated for combination with the iconoscope to equalize the gamma variations to a constant gamma approximately complementary with the monitor-tube gamma. Another nonlinear electrical network is advocated for combination with the orthicon to reduce the gamma of this camera to the same gamma as the corrected iconoscope camera. — A direct positive photographic technique is described using a negative monitor picture obtained by electrical phase reversal, and the toe region of the positive film characteristic. A general mathematical expression for the shape of the film toe as a function of the gammas of the television camera and monitor as required for linear over-all performance is derived. — The merits of such a photographic technique are economy, simplicity, rapidity of processing, and greater average screen brightness.