New answers tagged focus-point-selection
Phase detect autofocus in DSLRs works by comparing patterns of light coming from each side of the lens using pairs of detectors which are separated a certain distance on the AF sensor. This distance is called the baseline, and the greater the baseline the more accurately the distance can be measured. The need for a wide baseline and for light to travel from ...
Because autofocus needs a considerable amount of light, and the lens construction gives more light getting closer to the center. Also, lenses tend to be sharper the closer you get to the center. That is why using the middle focus point and then recomposing usually gives the sharpest result.
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