A slide projector is an optical device for displaying enlarged images on a screen. The projector is based on optical solutions used in a so-called laterna magica (magical lantern) – a simple device for displaying an image built of glass transparencies, where the light source was originally a candle flame and later a kerosene lamp or other chemical compounds. The invention of this device is attributed to Athansius Kircher, who described and illustrated it in 1646 in his work Ars Magna Lucis et Umbrae, and to Christiaan Huygens, who presented a working prototype in 1659.
The Diapol 9839 Automat slide projector was produced in 1975-1990 by Polskie Zakłady Optyczne in Warsaw. In the second half of the 19th century, one of the most prominent establishments producing optical instruments in Warsaw was Pierwsza w Kraju Fabryka instrumentów Optycznych FOS owned by Aleksander Ginsberg – the creator of the optical industry in the territory of Poland. After his death, the factory was probably moved to St. Petersburg. In 1921, however, it resumed operation in Warsaw as Fabryka Aparatów Optycznych i Precyzyjnych H. Kolberg i S-ka. After Kolberg retired from the company in 1930, the remaining shareholders established Polskie Zakłady Optyczne.
The design of projectors in the Diapol series was the joint work of Witold Woźniakowski, Jan Figlewicz and Zbyszek Kramarz. The external design of the projector was prepared by Jan Krzysztof Meisner – the designer of industrial forms, illustrator, photographer, design theoretician, and author of the designs for the Osa scooters, the Beskid car, and the Alfa and Druh photographic cameras.
The Diapol 9839 Automat projector is designed for projecting black-and-white or colour positive slides in the 24×38 mm format, framed in 5×5 cm frames. The projector’s optical arrangement uses the Krytar 2.8 lens with a focal point of 85 mm from 0.5 to 10 m. The device is equipped with a frame for the automatic feeding of slides. After the frame with slides passes from number 1 to number 36, the tray has to be manually moved to the first slide. Automatic slide changing and setting of image sharpness is enabled by the remote-control system. Thanks to the use of a strong halogen lamp, the projector can be used in home conditions, as well as in educational facilities. As the lightbulb generates a high temperature, a fan is installed in the projector to cool the optics. When using the device, pauses of 15 minutes were recommended after every 90 minutes of projection.

Authors: Beata Krzaczyńska, Piotr Turowski, Filip Wróblewski