Another critical objective when shooting in high definition is achieving a very sharp focus. The VIXIA HF21 camcorder features Canon's revolutionary Instant AF focusing system which offers a dramatic improvement in auto focus speed and accuracy (compared to traditional auto focus systems). The Instant AF feature uses an external sensor, in combination with Canon's auto focus system, to help significantly decrease the time it takes to find focus, even in low light conditions. This system achieves focus instantaneously, reducing focus "hunting." The benefits of Instant AF are especially seen in high brightness and night shooting situations. With Instant AF, it's possible to capture fast, accurate focusing, even when following a moving subject.
And because a properly focused subject is more critical than ever with HD, the VIXIA HF21 also features Focus Assist. This helps in capturing your subject in razor-sharp focus. It works by providing a 2x magnification of your subject (when you start recording, this assistance is automatically cancelled). This is a feature normally found in professional broadcast-quality cameras.