Meyer-Optik's Orestor 100mm f/2.8 — an East German M42 portrait telephoto with round bokeh.
The Meyer-Optik Gorlitz Orestor 100mm f/2.8 is an East German short-telephoto prime made in M42 mount from the mid-1960s. Produced by Meyer-Optik of Gorlitz, it was their portrait-length telephoto and became the basis for the later Pentacon auto 100mm f/2.8 after the works were combined.
This is a manual-focus M42 screw-mount lens with a 100mm focal length and a maximum aperture of f/2.8, with an automatic diaphragm. Focus and aperture are set by hand on the barrel, and it is known for a many-bladed aperture giving round openings. It is an all-metal short telephoto. Detailed element figures are not asserted here beyond the verified focal length and aperture.
At 100mm f/2.8 the lens is a portrait and short-telephoto tool, giving flattering compressed perspective and good subject isolation. Its many-bladed aperture produces notably round out-of-focus highlights, and it is popular among vintage users for pleasant, characterful bokeh that carried into the later Pentacon-badged version.
Used copies are affordable and popular for adapted portraiture. Inspect for haze, fungus and cleaning marks, confirm the many aperture blades are clean and oil-free, and check the aperture-ring and focus feel over the longer travel. Verify the M42 mount. An M42 adapter makes it a well-liked manual portrait telephoto on mirrorless.