Voigtlander's fast modern 35 — the Cosina-made Ultron 35mm f/1.7 in Leica Thread Mount.
The Ultron 35mm f/1.7 is a modern Cosina-made Voigtlander lens, released in 2000 as a fast 35mm for the Bessa screw-mount system. It is a contemporary manual-focus optic in Leica Thread Mount, not a vintage lens, and became a popular affordable fast wide-normal for rangefinder and adapted bodies.
It is a manual-focus rangefinder-coupled lens with a 35mm focal length and a maximum aperture of f/1.7. The design is compact for its speed, and the 35mm field is one of the most useful all-round focal lengths on full-frame rangefinder cameras.
The 35mm view suits street, reportage and general travel work, and the f/1.7 aperture gives room in low light and a moderate subject-background separation. Wide open the look is soft-edged and characterful; stopping down to f/4 or f/5.6 brings crisp, even results for everyday shooting.
As a newer Cosina-Voigtlander lens, used copies are typically clean and mechanically tight and remain widely available; the checks are smooth focus, clear glass and a positive aperture rather than age-related defects. It adapts to Leica M via an LTM ring and to mirrorless bodies with a simple adapter, making it a versatile fast 35mm.