Autofocus facts for kids
Autofocus is a clever feature in cameras that helps them take clear, sharp pictures. It's like a smart assistant that automatically finds the perfect focus for your camera's lens. This means your photos won't look blurry, but instead will be crisp and detailed. Autofocus systems are found in many devices, from your smartphone camera to professional digital cameras.
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How Does Autofocus Work?
Autofocus works by moving the camera's lens to the correct spot for a scene. Inside the camera, there's a special part called an image sensor that "sees" the picture. A tiny motor moves the lens, and the camera's computer brain constantly checks the image quality at each position.
Finding the Sharpest Image
As the lens moves, the camera measures how clear the image looks. It often does this by looking for sharp edges and strong differences in light and dark areas, which are called image gradients. The position where the image looks the sharpest and most detailed is chosen as the best focus. This whole process happens very quickly, so you can snap your photos without delay.
Speeding Up the Focus Process
To make autofocus even faster, many systems use a two-step method. First, the lens makes a quick, rough scan over its full range of movement. This helps the camera find a good estimated position for the focus. Then, in the second step, the lens makes smaller, more precise adjustments around that estimated spot. This fine-tuning ensures the focus is exactly right.
Improving Focus Accuracy
Sometimes, the camera can even use a trick called interpolation to make the focus even more accurate. This means it looks at the image quality from a few of the best positions it found. Then, it uses that information to calculate an even more precise focus point, making your pictures super sharp.
Images for kids
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Active autofocus system via infrared - Canon AF35M (1979)
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Early passive autofocus system integrated in the lens with Pentax ME-F (1981)
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See also
In Spanish: Autofoco para niños
