Rodenstock Apo-Ronar 300mm f/9 — apochromatic large-format process lens in Copal shutter
Rodenstock's Apo-Ronar line included a 300mm f/9 variant alongside the 240mm, part of a family of apochromatic process lenses built for large-format and technical photography from the mid-20th century through the film era. These lenses were used in studios, copy stands and view cameras rather than handheld SLRs.
Like other Apo-Ronar lenses, the 300mm f/9 is a symmetrical apochromatic design mounted via a lens board, normally supplied in a Copal shutter, with an image circle suited to 8x10in large-format use with front movements. Exact element count, weight and filter thread are not confirmed from a verifiable source and are omitted.
The design prioritises flat-field sharpness and minimal chromatic aberration over speed, making it well suited to product, architectural and reproduction photography where corner-to-corner accuracy matters more than a fast aperture.
These process lenses continue to attract large-format users for their optical accuracy. Buyers should test the shutter across its speed range, check the iris diaphragm operates cleanly, and confirm the lens board fitting matches their camera before buying secondhand.