Pentacon Auto 100mm f/2.8 - Sample Images
There is also a version of this lens called Pentacon electric 100mm f/2.8.
Also optically the same lens as the older Meyer-Optik Görlitz Orestor 100 f/2.8
Optical design: 5 elements in 4 groups
Lens mount: M42, Exakta
Covers: Full-frame (24×36mm)