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Is it common as a cinematographer to try and position the optical system in a manner where the entrance pupil serves as the axis of rotation, in order to prevent parallax (change in perspective) during camera movements? Is this only used in VFX or would it in theory also improve the naturalism of panning camera movements in general?

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.

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.

Hey y'all. Currently I am working on a Cine Lens Database to be able to provide free lens "data points" to the public. There's a lot of great information out there and the best DBs I found where these. https://www.fdtimes.com/2011/05/06/motion-picture-lens-database/ http://www.cinelensdb.com/ http://forum.mflenses.com/the-macrolenses-database-t78420.html Right now most of my work is filling in the gaps of Richard Bradbury's DB. It looks like not much has been updated in it since 2011. I reached out to him and cinelensdb.com, but no one got back if they were interested in continuing to update their projects. Currently I think it is a really good idea to attach these lenses with their respected "tech sheets" or "product brochures" in the excel I'm working on. Right now I need help finding the number of iris blades in the Ultra 16 set, as well as the entrance pupil sizes. I have linked the ARRI Ultra 16 Technical Details for all whom would like them. I have reached out to Zeiss, whom told me to contact ARRI for the missing data. I then reached out to ARRI, who told me to reach out to Zeiss. I'm thinking about reaching out to some lens servicing companies for the remaining data, however I think that might be a waste of time for a skilled technician to answer my email. Let me know what you think. THANK YOU FOR YOUR TIME!!!!