Critical Focus :

Critical focus can only be used with a zoom lens. As we interview a subject, we may want to start wide and then zoom in for a close up. Unfortunately, the subject may go out of focus. So, we set the critical focus. The camera will stay in focus as long as the distance between the camera and the subject does not change.

To critical focus:

1. Zoom in all the way on the subject.
2. Roll the focus ring until the subject is in focus.
3. Then zoom out to set up your shot.

The shot will stay in focus as you zoom in and out.

In sports, the camera operator does not have time to critical focus. Instead they focus on the fly. The operator has one hand on the hand grip and the other on the focus ring. As the subject moves, the operator uses both the focus ring and zoom control to keep the subject in focus and in frame.

Tip: If you are doing an interview, zoom in and focus on the eyes. This way the face stays in focus.

Click on the icons below to view a good Critical Focus and a not so good Critical Focus.

Not so Good - The focus is on the background and so the subject is out of focus if you zoom into a close up.