Phone Camera App to Record Projection

[Chris Smart]

Hello everyone!

Does anyone know of a camera app that can help reduce or eliminate the flickering one sees when trying to record a film with your phone while projecting on a wall? I remember seeing a post about this somewhere but could not find it using the search function.

[Janice Glesser]

I think like recording any film with a camera you need to have a variable speed projector. This way you can adjust the speed to minimize the flicker.

[David Strelitz]

I think like recording any film with a camera you need to have a variable speed projector. This way you can adjust the speed to minimize the flicker.

...and/ or a camera with a variable shutter or Clearscan, (which is only found on Pro level cameras).
That said, Neat Video can be used to remove strobing. I have never used it for cine transfer, as my telecine is set up correctly but I did use in post for a recent theatre shoot when some projected backdrops were strobing. Results were excellent albeit needed 100% computer rendering for playback.

[Thomas Dafnides]

If your phone cam has settings for shutter speed and/or frames per second...you might try experimenting with those. You might be able to reduce the flicker to be less objectionable.

[Nantawat Kittiwarakul]

If your phone's camera does have some sort of "pro" video mode allowing you to varying the shutter speed, it might be possible to use your phone. Adjusting the shutter to match the projector's speed as closely as possible (1/50 second should be a good start). The flicker could be kept minimal, or if you're lucky - completely eliminated.

One other issue remains however.

You'll have to figure out how to control the brightness of the captured image. My phone can vary the ISO setting in Pro mode so that would be used - you'll have to figure out for your own case then.

[Douglas Meltzer]

I've seen apps for phone cameras that allow you to set the shutter speed while in still mode, but not when shooting video. The ISO and exposure can be set, however there are no adjustments to the shutter. Has anyone come across an app where this is possible?

Chris, does your phone have a 24fps setting?

[Stan Jelavic]

Open camera for Android has time lapse mode with the following divide ratio:
1,2,3,4,5,10,20,30,60,120 and 240
It is platform dependent so some phones do not support it but it is worth a try.
Interestingly enough I just tried using a Chinon Whisper transport with the T3i camera and Laowa macro lens and the stepper with a synchronous video capture at 3FPS. Got some very good results but the issue is that the setup and the post is quite complicated. So went back to the asynchronous transfer with a DC motor at around 6 FPS and lots of banding.
Then used the Getdups avisynth plugin to clean up the video and the results are very encouraging. Once the threshold is set properly you get only a few small bands for 3500 frames. Will post the resulting video tomorrow.
But anyways this could be probably used with the cellphone combined with the microscope. The camera can be run at 30 FPS (no need for new camera app) and run the projector below 8FPS and then clean up the video with Getdups.
Here is more info on Getdups:
https://www.avisynth.org.ru/getdups/getdups.html

[Stan Jelavic]

Here is the test video.
https://drive.google.com/file/d/18p7...ew?usp=sharing
It still has some shimming (jello effect). Check the tower in the video.
It could be due to motor vibration and that Resolve stabilization is not correcting it.
I will try the new motor rubber mounts tomorrow. It may help.
But it could be other causes such as the rolling shutter effect at low projector fps.
Or Getdups not filtering some transitions. More work to do.

[Janice Glesser]

Stan Jelavic Yes Stan... Maybe rolling shutter effect, however an impressive transfer nonetheless! Achieving 100% in film transfers is a challenging never-ending battle... But a battle worthy of the efforts... And fun too! Love all your work!

[Stan Jelavic]

Thank you Janice. As you said it, it is a never ending battle. The main thing is not to forget to have fun despite all the difficulties and hurdles.

[Stan Jelavic]

The new motor rubber mounts worked out quite well. Did not use the Resolve stabilizer this time just Getdups.
https://drive.google.com/file/d/10VJ...ew?usp=sharing
The projector was run at 6 fps and the camera at 30 fps.

[Stan Jelavic]

I think my posts here are diverging a bit from the original one posted by Chris. It is not totally off because the getdups plugin could potentially be used if you grab the video with your cellphone. You would have to transfer the video into a pc and then process it there.
But some people probably want to go the easy route and are not too concerned with the final video quality. For those here is one way of doing it:
- project your video onto a wall or a white screen.
- record the video with you cell phone.
- breakup the video into individual frames:
https://www.guidingtech.com/extract-...video-android/
- run the image cleanup:
https://www.makeuseof.com/tag/androi...leting-photos/
- reassemble the final video
https://www.maketecheasier.com/best-...o-from-photos/

These are the apps that I found by doing a quick search and may not be the best choice since I never tried them. So you will have to do your own search and do some experimenting in order to get acceptable results.

It also may be a good idea to try a microscope connected to the cellphone instead of projection. The video quality would definitely be much better. This would also require a mod to the light which is not too hard to do.

[Kirk Anderson]

I've been using ProCam on my iPad for this. Shutter speed and everything else can be manually controlled. And it has excellent editing tools... which are sometimes beyond what my older iPad can handle.

[Stan Jelavic]

Do you use synchronous or asynchronous transfer Kirk or frame by frame?

[Kirk Anderson]

Stan, I think the answer is synchronous. Definitely not frame by frame. Frame rate on ProCam, to clarify, is not continuously variable. Typically I have to choose 24 or 48 fps. At the higher numbers, the flicker becomes a solid black bar, which I cannot "dial out" for more than a few seconds because projector speed is not steady enough, regardless of the projector. I wish that ProCam allowed user-defined settings templates so I wouldn't have to configure every setting each time I open it. It's a bit of a pain. This is still an experiment.