Why autofocus snaps so fast

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Contrast detection feels like a tiny hunt, pushing the lens back and forth until the image reaches peak contrast, which makes it very accurate but slower<sup class="text_citation" source_id="1"></sup><sup class="text_citation" source_id="4"></sup><sup class="text_citation" source_id="5"></sup>.

Phase detection is the snap lock, comparing two images to tell the camera which way to move the lens and roughly how far<sup class="text_citation" source_id="1"></sup><sup class="text_citation" source_id="4"></sup><sup class="text_citation" source_id="5"></sup>.

That is why phase detection is ideal for fast-moving subjects, while contrast detection shines on still subjects where precision matters most<sup class="text_citation" source_id="1"></sup><sup class="text_citation" source_id="4"></sup><sup class="text_citation" source_id="5"></sup>.

Modern mirrorless cameras often blend both systems, and Canon's Dual Pixel CMOS AF puts phase detection on the sensor itself for smooth tracking<sup class="text_citation" source_id="1"></sup><sup class="text_citation" source_id="4"></sup>.