The rapid rectilinear is a lens system composed of two matching doublet lenses arranged symmetrically on either side of the aperture. Introduced by Dallmeyer and Sternheil, this design significantly reduced many of the optical aberrations-such as distortion and curvature of field-common in simpler lenses of the 19th century.
Rapid rectilinear lenses became popular for landscape, architectural, and portrait photography, offering sharper images and more accurate rendering of straight lines. Its balanced design laid the groundwork for many modern lens constructions and remains a key development in the history of photographic optics.