The earliest cameras (1926-1933) were generally flying spot scanner types. A bright light source, such as an arc lamp, was focused through a Nipkow disk and a lens onto the subject being televised. A spot of light moved across the subject, reflected off, and was captured by a photoelectric cell, which produced the video signal. Televising was limited to indoors, in almost total darkness.
Mechanical Broadcast Equipment in the Museum's Collection
Flying Spot Scanner Camera