in accordance with light-reducing "factor" of filter or other obturator used with or on the lens of the camera

Full Title

Control of exposure by setting shutters, diaphragms or filters, separately or conjointly (control of exposure in television cameras by means of circuitry influencing the optical part of the camera H04N23/75) > in accordance with light-reducing "factor" of filter or other obturator used with or on the lens of the camera