A deluxe Mackenstein hand-held stereoscope with a burr walnut finish for 8,5x17cm stereoviews. The viewer is suitable for paper card stereoviews and glass slides.
The lenses can be focussed and the distance between the lenses is adjustable. It emphasises the luxury of the viewer, because interocular adjustment is not a common feature for hand-held viewers. Striking are the two large lenses. They look impressive, but cannot be entirely covered by the eyes and cause reflections. The viewer has no blinders to block incident light. When incident light is shielded, the stereoscope provides a pleasant viewing experience.

The stereoscope bears a nameplate of the renowned camera manufacturer Établissements Mackenstein from Paris. Mackenstein designed their own stereoscopes[1], but also sold rebranded stereoscopes that were manufactured by Mattey[2]. This viewer is most likely built by Mattey.
References
- Mackenstein, Appareil stéréoscopique pour la vision des épreuves photographiques sur verre et sur papier n° FR471602, 5 November 1914 – via data.inpi.fr
- A stereoscope with Mattey’s trademark 8&9 bears a Mackenstein label