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About Critical Focus

Critical focus is the portion of a shot that is exactly in focus. It describes something that is exactly in a certain plane at a specific distance, dependent on the focal length of the lens. The formula that describes this relationship is 1/I + 1/O = 1/F, where I is the distance between the lens and the sensor, O is the distance from the lens to the plane of critical focus, and F is the focal length of the lens.

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