From LibreTexts, under CC BY-NC 4.0, as the source states it; its equations are written in TeX, which the PDF shows typeset. This page at LibreTexts.
8.6: Critical Focus
Opening the book…
A Critical Focus is performed to ensure that the subject is in focus. Once you have executed a cricital focus, if the distance between the subject and the camera does not change, your focus should hold. You can zoom in and zoom out and your subject should remain in focus.
Figure \(\PageIndex{1}\): Performing a critical focus on the eyes. (CC BY-NC 4.0; Shelley Ho via San Francisco State University)
Steps to Perform a Critical Focus
Zoom all the way in on your subject. If the subject is human, focus on the eyes
Use the focus ring to achieve focus
Zoom back out and compose your shot
You can see an example of a critical focus in Figure \(\PageIndex{1}\).
Focus Assist and Focus Peaking
In chapter 7, we discussed Focus Assist and Focus Peaking, which is an overlay guide to show where things are in focus. You can turn that function on to assist with your critical focus.