Autofocus system and evaluation methodologies: A literature review

Abstract

The autofocus (AF) system has gained popularity in over 40 years. Embedded in a camera, it can bring the best focused image to the viewer within a few seconds, which frees users from focusing manually. An AF system usually consists of a motor, a lens, and the processing and control units. Within years of development, the AF system has become mature in terms of both technology and market, and many fast and accurate AF systems have been introduced and widely installed in compact cameras and digital single lens reflex (DSLR) cameras. On the other hand, the market for thermal infrared cameras has been increasingly growing in recent years owing to their decreasing cost and wide use by both civilians and the military. The AF system in those cameras adopted similar but more complex mechanisms. This article serves as a literature review of the state of the art of the AF system in both visible light digital cameras and thermal infrared cameras.