A magazine-fed stereoviewer for medium format (6 × 13 cm) glass slides. (A smaller cartridge for 45 × 107 mm was also available.) The magazine holds twelve slides, each held in a special metal frame. Pushing the cartridge in recaptures the slide currently in the viewer; pulling the cartridge out inserts the next slide (Fernández 2025). Focus is controlled by turning a knob attached to a rack and pinion that moves the lenses in and out. Interocular separation is controlled by a second knob that turns a rod with opposing helical threads that move the lenses in opposite directions. As with all magazine-fed viewers, additional cartridges were available for purchase.

The Planox Apescope was invented by Albéric-Alfred Plocq, who received a French patent for it in 1929 (FR 667104) (Martiné 2026). Plocq worked at the company Établissements A. Plocq, started in 1895 by his father, Alexandre Plocq.