Kontrastdetektering

Kontrastdetektering, also known as contrast detection autofocus (CDAF), is a method used by digital cameras to achieve focus. It relies on measuring the contrast of the image as perceived by the camera's sensor. The camera analyzes the sharpness of the image at different points and adjusts the lens until the contrast is maximized. This indicates that the image is in sharp focus.

In practice, the camera's autofocus system will move the lens elements back and forth, taking multiple readings of image contrast. It identifies the position where the contrast is highest. This is typically achieved by looking for the sharpest edges and details within the scene. CDAF is a relatively simple and computationally inexpensive autofocus method. It is often used in mirrorless cameras and compact cameras due to its efficiency and low power consumption.

While effective, contrast detection can sometimes be slower than other autofocus methods, such as phase detection. This is particularly true in low-light conditions or when tracking fast-moving subjects, where contrast levels can be low or change rapidly. Despite this, advancements in algorithms and sensor technology have significantly improved the speed and accuracy of contrast detection systems. Many modern cameras combine CDAF with other autofocus techniques to offer a robust and versatile focusing solution. The inherent simplicity of CDAF also makes it well-suited for live view focusing on DSLRs.