A slow lens is a camera lens that has a relatively small maximum aperture, such as f/8, limiting the amount of light that reaches the film or sensor. Because of this, slow lenses require longer exposure times or brighter lighting conditions compared to lenses with larger apertures.
Slow lenses are often used in landscape, architectural, and studio photography where depth of field and sharpness are prioritised over low-light performance, providing precise control over focus and image quality.