technikum29 

Museum for the historical development of calculator, computer and communication technology

Saba Telerama: Schmitt lenses

Telerama-Schmitt-Optik

The Schmitt lenses, demounted from the Saba Telerama projection TV-set.

The CRT (6 cm diameter) is partly visible in the pice. The light coming from this tube caroms on the concave mirror (in the picture laying on the floor). Afterwards it is adjusted by an special lens (on the right of the box) and leaves the box, arriving at the projection screen.
During this long way the original picture which is about 4,5cm x 3,5cm big is scaled up to 123cm x 97,5cm on the projection screen. Consequently, the luminosity is decreasing enormously. If you compute the final fraction of the original luminosity, you'll understand, why this projection TV had to be set in a totally shaded room.