Blendenverlauf

Blendenverlauf, a German term, translates to "aperture gradient" or "diaphragm gradient." In the context of photography and optics, it refers to the gradual change in the aperture setting or the resulting depth of field within a single image. This phenomenon is not a standard photographic setting but rather a descriptive term for how the aperture's effect varies across the frame.

While a camera typically has a single aperture value for a given exposure, the visual perception of sharpness and blur can appear to change due to various factors. For instance, a photographer might intentionally compose a shot to have a sharp foreground subject with a progressively blurred background, creating a visual gradient of focus. This is achieved by carefully selecting the focal length, subject distance, and aperture.

Alternatively, in very wide-angle lenses or certain optical systems, there can be a subtle, inherent variation in depth of field across the frame, though this is usually less pronounced than intentional creative choices. The term "Blendenverlauf" can also be used to describe how the perceived effect of the aperture changes from the center of the image towards its edges, especially in lenses that exhibit vignetting or where focus is not perfectly uniform. It's a way to articulate a nuanced visual characteristic of an image rather than a direct camera control.