Make Autofocus Work for You and Sharpen Your Images

by camerarepair on

autofocus unit

Digital Compact Cameras, also known as Digital Point & Shoot Cameras, share a simple basic attribute: the lens. The lens is permanently attached and often retracts to some degree back into the camera when powered off. Digital cameras like this have an autofocus mechanism that operates using three basic parts; the image sensor, the lens elements and the autofocus unit. Keep reading if you’d like to learn how all of these features work together to sharpen your images.

Focusing an image all starts with the lens elements; in fact it is the elements that allow focus to take place. They are also what gather and funnel the light that is eventually projected onto the digital sensor. As a user zooms in and out the focal length changes and how that light can be interpreted changes as well. The amount of light is restricted along with the angle of view as the focal length increases. To put it simply, as you zoom in, less light comes in and the focusing range changes.

Believe it or not, the sensors job isn’t limited just to capturing the image. When light comes in from the lens and hits the sensor you typically get a preview on the LCD screen. The cameras processor is also receiving a preview and trying to make sense of what it sees. The more available light, the easier the job is (which is why when you are in a dark room, some cameras give off a red/orange light while focusing). By and large, most compact digital cameras use a type of autofocus called “contrast measurement”. This works by measuring intensity levels between pixels that are next to one another. When maximum contrast is achieved, the processor deems the image is in focus. There is no distance measurement done as is done with typical SLR autofocus systems (called phase detection).

Although the other focus mechanisms play an important role, the lens assemblies autofocus unit is the real workhorse of the whole operation (post image). This part is located in front of the sensor after both the shutter and aperture mechanisms and is the last lens element along the line before hitting the sensor. As the contrast data is processed, signals are sent to the AF unit to move the element back and forth to focus the projected image on the sensor. This unit isn’t attached to the rest of the lens assembly but rather is usually attached to the body of the camera. Camera repair services such as us often see this stop working due to dust or debris build up on the gears that drive the element. When that happens, the whole camera requires disassembly and the gears and motors are repaired and cleaned or replaced.

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