Search the Community
Showing results for tags 'focus at entrance pupil'.
-
According to AC Magazine April 2020 edition " The Pupil Marks the Focus Spot The next thing to understand about the entrance pupil is that it is at that point — not at the film plane (or sensor plane) — from which focus should be measured. It’s a long-standing practice in cinematography to take focus measurements from the film or sensor plane of the camera. " (read the attachment) Well, the topic seems to be fine and interesting but, the basic question is never raised nor answered - WHY FOCUS SHOULD BE MEASURED FROM ENTRANCE PUPIL? Can some one explain these : 1) Do all of the points of light from the scene converge to a single point at the entrance pupil and then expand back out to the image plane ? 2) What role does exit pupil play in measuring focus ? 3) Can Iris be located not at aperture stop ? 4) How is DoF related to entrance & exit pupil ? And please provide a reference website or material to understand these technical concepts clearly. Thanks, Ram Nanda.
- 17 replies
-
- focus
- entrance pupil
-
(and 2 more)
Tagged with:
-
According to AC Magazine April 2020 edition " The Pupil Marks the Focus Spot The next thing to understand about the entrance pupil is that it is at that point — not at the film plane (or sensor plane) — from which focus should be measured. It’s a long-standing practice in cinematography to take focus measurements from the film or sensor plane of the camera. " (read the attachment) Well, the topic seems to be fine and interesting but, the basic question is never raised nor answered - WHY FOCUS SHOULD BE MEASURED FROM ENTRANCE PUPIL? Can some one explain these : 1) Do all of the points of light from the scene converge to a single point at the entrance pupil and then expand back out to the image plane ? 2) What role does exit pupil play in measuring focus ? 3) Can Iris be located not at aperture stop ? 4) How is DoF related to entrance & exit pupil ? And please provide a reference website or material to understand these technical concepts clearly. Thanks, Ram Nanda.
-
- entrance pupil
- focus
-
(and 2 more)
Tagged with: