L’Astra is the largest of Bize’s designs. The slide tray mech­a­nism of L’Astra dif­fers from typ­i­cal stere­o­scopes. Instead of a tray car­riage mov­ing over a rail, L’Astra uses a gear sys­tem embed­ded in the base plate, with the tray fea­tur­ing grooves. The rotat­ing gear moves the tray smooth­ly for­ward, ensur­ing pre­cise posi­tion­ing of the slides. A tray can hold 24 slides. A knob on the left side allows nav­i­ga­tion to a spe­cif­ic slide.
The base of the view­er con­tains two draw­ers with 3 trays each result­ing in 144 slides in total.
Lat­er mod­els of L’Astra were designed to sup­port the view­ing of autochromes, with a spe­cial mech­a­nism to accom­mo­date the thick­er glass plates used for col­or slides. There was also a ver­sion for 45x107mm slides.

Fur­ther read­ing: Stere­oscopy His­to­ry Series — Lucien Bize (A. Ruiter)