Fookuskaugus

Fookuskaugus is the optical distance between a lens’s main reference point and the image plane (the sensor or film) where incoming light rays are brought to focus. In the thin-lens model, it is the distance from the lens to the image plane, and for objects at infinity the image is formed at the focal plane. Fookuskaugus is typically expressed in millimeters and is a property of the lens itself.

In photography and optics, the focal length largely determines the field of view and magnification. Shorter focal lengths yield a wider angle of view and less magnification, while longer focal lengths provide a narrower angle and greater magnification. The same focal length can produce different results on cameras with different sensor sizes; the sensor size affects the actual field of view, leading to the use of terms like 35mm equivalent focal length.

Lenses are commonly described by their focal lengths, and typical ranges include wide-angle, standard, and telephoto categories. Wide-angle lenses (short focal lengths) capture a broader scene; standard lenses (around 50 mm on full-frame sensors) approximate natural perspective; telephoto lenses (long focal lengths) magnify distant subjects and compress depth.

Understanding fookuskaugus also involves considering depth of field and perspective, both of which depend on focal length, aperture, subject distance, and sensor size. It is a fundamental specification in lens design and choice, guiding decisions about composition, perspective, and image scale.