Editing Kinescope (section)

=== Lenses ===

Lenses did not need a great depth of field but had to be capable both of producing a very sharp image with high resolution of a flat surface and of doing so at high speed. In order to minimize light fall-off on the perimeter of the lens, a coated lens was preferable. 40&nbsp;mm or 50&nbsp;mm lenses were usually used with 16&nbsp;mm in calibrated mounts. Focus was checked by examining a print under a microscope.