Linsenstufen

Linsenstufen, a German term translating to "lens steps" or "lens stages," refers to a historical type of photography lens characterized by a series of adjustable apertures, or stops, built directly into the lens barrel. Instead of a rotating diaphragm, Linsenstufen lenses featured multiple physical openings of varying sizes that could be manually selected by moving a small lever or ring along a calibrated track. Each step corresponded to a specific aperture value, typically marked with numbers like f/4, f/8, f/16, etc. This design was common in early to mid-20th-century cameras, particularly among large-format and medium-format cameras.

The primary advantage of Linsenstufen was their mechanical simplicity and robustness. They were less prone to malfunction than early diaphragm mechanisms and offered a clear, tactile indication of the chosen aperture. However, they also had drawbacks. The range of available apertures was often limited compared to modern irises, and making fine adjustments between stops was impossible. Furthermore, changing aperture required physically moving the lens element or a separate component, which could be slower and more cumbersome than rotating a diaphragm ring. While largely superseded by more sophisticated diaphragm designs, the Linsenstufen concept represents an important evolutionary step in the development of photographic lens technology.