Viewer for a stereoscopic photograph

Viewer for a stereoscopic photograph. Negretti & Zambra. Magic stereoscope. Desktop stereoscopic photo viewer (17. 7 x 8. 8 cm) with two circular lenses (5 cm diameter) and two more pairs inside the device. Apparatus to view stereoscopic photographs, producing a relief effect. It consists basically of two lenses, each of which was used only to view one of the two images of the stereoscopic photograph. The lighting could be natural through a piece of glass polished with emery behind the photography or an opening in the upper part of the apparatus, or it could be artificial. There were many types of view-finders: folding, tabletop, columns or handheld. They were used especially in the second half of the nineteenth century and the fist half of the twentieth century.