Jacob Mitchell Posted February 25 Share Posted February 25 Hi all, I recently shot with my first rear projection screen, and not until we were shooting did I notice a feeling of “lag” or “drag” in what was being projected. Talent was directly up against the screen, with top down footage of ocean waves going by. I felt a very, very subtle stutter in the footage that was not perceivable by eye. Unfortunately this was an incredibly rushed setup so did not have time to ask for specs/adjustments. Could anyone advise as to what may cause this, and what solutions may exist? Quote Link to comment Share on other sites More sharing options...
Premium Member Phil Rhodes Posted February 25 Premium Member Share Posted February 25 Tricky to say without being able to see it. There's a number of places issues can arise with this sort of thing. Can you post footage? Quote Link to comment Share on other sites More sharing options...
Jacob Mitchell Posted March 1 Author Share Posted March 1 Not yet, will try once it’s released Quote Link to comment Share on other sites More sharing options...
Robin Phillips Posted March 1 Share Posted March 1 was it a virtual rear projection setup (aka the camera being tracked with an unreal or similar background)? Do you recall the projector settings? Was it a 144hz projector or less? Was what you saw on the monitor or to the eye (or both)? Was the camera on battery or was it running house power? Was it on the same circuit as the projector or a different one? Do you recall the playback file's frame rate and the camera's frame rate? Do you recall the device (and if a computer, the software) used to playback your projected material? Quote Link to comment Share on other sites More sharing options...
Joerg Polzfusz Posted March 2 Share Posted March 2 Could this be something like the „wagon wheel effect“? https://gizmodo.com/why-do-wheels-sometimes-appear-to-spin-backwards-1593807400 Quote Link to comment Share on other sites More sharing options...
Joerg Polzfusz Posted March 2 Share Posted March 2 Or something like the „rolling shutter effect“? https://en.wikipedia.org/wiki/Rolling_shutter Quote Link to comment Share on other sites More sharing options...
Joerg Polzfusz Posted March 4 Share Posted March 4 (edited) Or could it be caused by the source material? (Something like the https://en.wikipedia.org/wiki/Three-two_pull_down or another „conversion error“ or a computer having problems displaying the video fast enough (usb-stick too slow, strange codec,…)?) Edited March 4 by Joerg Polzfusz Quote Link to comment Share on other sites More sharing options...
Jacob Mitchell Posted March 6 Author Share Posted March 6 On 3/1/2023 at 10:13 AM, Robin Phillips said: was it a virtual rear projection setup (aka the camera being tracked with an unreal or similar background)? Do you recall the projector settings? Was it a 144hz projector or less? Was what you saw on the monitor or to the eye (or both)? Was the camera on battery or was it running house power? Was it on the same circuit as the projector or a different one? Do you recall the playback file's frame rate and the camera's frame rate? Do you recall the device (and if a computer, the software) used to playback your projected material? Questions I wish I had the answers to. Wasn't the most friendly projection team unfortunately. But, it was a rear projection setup that was pre-recorded footage from out in the world, what I saw in the monitor was not the same as what I saw in my eye. To the eye it looked perfectly smooth. Almost like the hertz refresh rate was causing the problem for camera. Camera was on battery power. Thats about all the answers I have. Quote Link to comment Share on other sites More sharing options...
Robin Phillips Posted March 6 Share Posted March 6 I think without the answers to those questions we cant really know. I can tell you a while back a show I was on we just bought a $800 projector off amazon, I believe it was 60hz. playback was 30fps because of the approved background (which was licensed, annoyingly only came at 30fps) while we recorded 24fps. We were on battery, no phase sync. Looked great. Given the projector was 60hz I believe it was showing each frame twice on playback. We ran the playback off my macbook pro with the screen mirrored via HDMI. We tried a 24fps conversion on the 30fps stuff the day before we shot, and that caused an image stutter, but the stutter was visible to the eye as well as on the monitor. That led us to go back to the original frame rate. Quote Link to comment Share on other sites More sharing options...
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