Limiting aperture refers to the actual size of the opening created by a lens's iris diaphragm at a given setting. This physical aperture controls how much light enters the camera, directly affecting exposure, depth of field, and image sharpness.
Understanding the limiting aperture is important for photographers who want precise control over their images. By knowing the actual aperture size, photographers can make informed decisions about exposure, achieve desired depth-of-field effects, and optimise lens performance for both creative and technical photography.