Aperturen

Aperturen refers to the plural concept of aperture in optics and photography. The aperture is the opening in a lens or optical system that allows light to reach the image plane. In English-language photography, the singular is aperture and the plural is apertures; the form Aperturen appears in German-language texts and in some technical contexts to denote multiple openings.

Aperturen are created by a diaphragm composed of overlapping blades that form a variable opening. The size is commonly described by the f-number, f/N, which equals the focal length divided by the effective aperture diameter. A smaller f-number indicates a larger opening and brighter exposure; a larger f-number indicates a smaller opening and darker exposure.

The aperture influences depth of field: large openings yield shallow depth of field, while small openings increase depth of field. It also affects diffraction: at very small apertures, image sharpness can degrade due to diffraction. The shape of the aperture blades can affect the bokeh of out-of-focus points, influencing the appearance of highlights and background blur.

In practice, photographers balance aperture with shutter speed and ISO to achieve the desired exposure and depth of field. Aperturen concepts also apply in microscopes, telescopes, and other optical instruments where transmitted light influences resolution, contrast, and image quality. Modern lenses employ iris diaphragms with mechanical or electronic control, often offering automatic exposure modes as well as manual adjustment of the opening.