TTL focusing has transformed modern photography.
Through the lens (TTL) auto-focusing has transformed professional and amateur photography. Manufacturers can produce "point-and-click" cameras that do not need manual focusing before taking a picture. TTL focusing technology simplifies photography and increases your chances of snapping a crisp image.
Purpose
TTL systems use light passing through the lens to perform various calculations, such as automatically adjusting the focus, aperture or shutter speed to ensure photographers capture a crisp, well-exposed image.
Function
TTL lets photographers aim, depress the shutter release button and not worry about focusing the image -- the camera's electronics identify the main feature in the image and focus on it automatically. Focusing options in the camera menu allow some control over how the camera selects the focus, the rest is automatic.
Process
There are two common auto-focus systems: Active systems and passive systems. Active systems bounce light or sound waves off the subject. The time they take to return to the camera is used to find the distance. Passive systems split the light entering the lens into two beams, forming a basic range finder, or they measure the contrast in the image and adjust the focus until the strongest contrast is achieved.
Tags: Active systems, systems Active, systems Active systems
