Pincushion distortion is a type of optical distortion that occurs in images captured by certain lenses, particularly wide-angle and telephoto lenses. This distortion causes straight lines to appear curved inward towards the center of the image, resembling the shape of a pincushion. It is most noticeable at the corners of the frame, where the effect is more pronounced. This phenomenon is often contrasted with barrel distortion, where lines bulge outward. Pincushion distortion can affect various types of photography, including landscape photography and portrait photography, and is important for photographers to understand when selecting lenses for their work.