Buhl Mobile Multiplexer
The Buhl Mobile Multiplexer with telecine projector and 3
CCD camera with 800 lines of horizontal resolution.
Buhl optical systems form an intermediate "aerial" image from one of the source projectors. The television camera "looks" at this image in mid air, creating the brightest and most colorful image possible.
Explanation of Field Lens and Rear Projection Screen
Illustration A shows that without a field lens or a screen at the image plane, only the light coming through the very center of the image gets into the camera lens. The corners are not illuminated. Only a small circular field is visible.
Illustration B shows that when the image is projected onto a rear projection screen, it can be seen by the unassisted eye as well as the video camera, but there is considerable light loss due to the screen's bend angle. Image quality is lost due to grain in the rear projection screen.
Illustration C shows that a field lens located at the aerial image directs light from all parts of the field lens into a small circle. When the camera lens is placed at this circle, the entire field is illuminated. This is the system we use for the highest quality image.