Couldn't you make a film camera that was silent by rotating an array of lenses? - Page 1
Forum section: electronics / general

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: August 14, 2023, 01:21:16 pm
content: So instead of moving to the next frame, "stopping" the film for the exposure time, and then moving to the next frame. Instead move the film continuously and have a rotating array of lenses that follows the light to each frame without needing to stop the film on every time? Thereby making the camera near silent.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 14, 2023, 01:41:05 pm
content: Quote from: ELS122 on August 14, 2023, 01:21:16 pmThis is how some high-speed film cameras worked, using prisms or mirrors. You probably still need a shutter though

author: vad
author_rank: Frequent Contributor
timestamp: August 14, 2023, 02:51:04 pm
content: Even the slightest speed mismatch, jitter, film movement in a direction perpendicular to the plane of prism rotation, or lack of film flatness during motion would degrade image quality. Resolving all these mechanical issues is possible, but it would entail enormous complexity and cost, making it impractical for the mass consumer market.

author: vad
author_rank: Frequent Contributor
timestamp: August 14, 2023, 03:31:52 pm
content: Well, IMAX is focused on achieving the highest possible image quality. It's likely unfeasible to achieve the same level of quality using a continuously moving film without making the camera excessively large, heavy, expensive, or unreliable.

author: TimFox
author_rank: Super Contributor
timestamp: August 14, 2023, 03:37:43 pm
content: Rotary disc shutters are often used for motion-picture cameras:https://en.wikipedia.org/wiki/Rotary_disc_shutter

author: vad
author_rank: Frequent Contributor
timestamp: August 14, 2023, 03:51:53 pm
content: According to Wikipedia, the noise from IMAX cameras originates from the vacuum system. The vacuum is applied to the backplate to maintain the flatness of the tremendously large film frame during exposure.In the case of a hypothetical camera with a continuously moving large format film, the challenge of ensuring film flatness would still need to be addressed, now for a moving film frame. This would require either finding an alternative solution without a vacuum or using the same noisy vacuum system.

author: TimFox
author_rank: Super Contributor
timestamp: August 14, 2023, 03:57:56 pm
content: Note that “full” IMAX cameras transport medium-format film (70 mm, similar to 2-1/4 inch 120 still film) horizontally through the camera, rather than the vertical transport in conventional movie cameras.There is an interesting panoramic film still camera (modern version sold as “Widelux”, q.v.) that pivots the lens mechanically to cover roughly 150 deg.

author: TimFox
author_rank: Super Contributor
timestamp: August 14, 2023, 04:18:17 pm
content: What type of vacuum pump is used here now?For this application, one does not need a “high” vacuum (very low absolute pressure) but a high pumping speed to pump air against a high leak around the film handling.

author: TimFox
author_rank: Super Contributor
timestamp: August 14, 2023, 04:24:45 pm
content: How would you “delimit” the frames from each other?

author: Siwastaja
author_rank: Super Contributor
timestamp: August 14, 2023, 04:30:47 pm
content: Quote from: mikeselectricstuff on August 14, 2023, 01:41:05 pmYes, and film editing tables, too, to project the image on a screen in continuous film motion.https://en.wikipedia.org/wiki/Steenbeck#/media/File:Steenbeck_16mm_flatbed_ST_921_(6498601571).jpg(I had the same model as pictured lying around, but gave it away. It was nonfunctional due to so much aged electronics, poor connections, capacitors etc.)In this use case, small amount of image distortion, jitter etc. is not a problem at all.

author: mendip_discovery
author_rank: Super Contributor
timestamp: August 14, 2023, 06:01:00 pm
content: They can get up to 120db but reading an article in them they also state they use a rotating mirror to record sound...odd but I'm not a camera tech. But the sound they record is really high quality.I think that loud cameras on set is nothing new, they just had different solutions to it back then. I wonder if it's the directors who are great visionaries but as nobody will tell them no so they want to do a wide shot and a close up but don't want any of the sound gear or film gear anywhere near the set.I thought with the size of microphones they could hide many on set to get good sound.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 14, 2023, 06:16:29 pm
content: Quote from: ELS122 on August 14, 2023, 01:21:16 pmIIRC that's exactly how very high-speed film cameras worked, like in the 1980s. I remember seeing some sort of lab footage from a "Star Wars" SDI experiment, and there was a vrooooup! sound just before the test, later I found out that's the rotating prism of the high-speed camera.