Real Time Synchronous Transfer

[Stan Jelavic]

Have seen several implementations of real time synchronous transfer from a projector to a Video Cam or DSLR. Here is one of the older implementation using the discrete components:
http://djcarlst.provide.net/19960525.htm
I wanted to do something similar using a DSLR in hi rez video mode, taking the Vsync to sync the motor. An IR sensor can be used on the cam blades as the compare input. The idea sounds pretty doable to implement but I never had enough motivation to try it. Wonder if anyone in this forum tried it.
Here are some details.
Use the MSP430 as the main controller of the system.
The motor steed is checked by the optocoupler. Something like this one:
Digikey 511-1351-ND
The camera HDMI connected to the HDMI-VGA adapter
https://www.amazon.com/dp/B075GZ8DX7
Route the optosensor and Vsync from the VGA adapter into the MSP.
The sw then compares the two signals using the MSP430 interrupts, similar to this:
https://circuitdigest.com/microcontr...omposer-studio

The MSP then adjusts the motor speed by changing the PWM duty cycle
https://www.ti.com/lit/an/slaa497/sl...oogle.com%252F
https://coder-tronics.com/category/msp430/page/2/

The PWM signal then can be fed into the motor driver.
https://media.digikey.com/pdf/Data%2...RI0002_Web.pdf

With this setup the camera records at 30FPS. The cam speed in lock state is at 20 FPS and with 3 blades it is 60 pulses per second.
Since the motor is locked to the camera sync, no flicker should be present in the captured video.

[Stan Jelavic]

https://photos.app.goo.gl/pqwJjyJMECAW7Enr7
Here is another one of my little projects. Took the Chinon transport out and mounted it on the board. Added the stepper that runs at 3 FPS. The light is just an old video light mounted one the lens side. The camera is Canon T3i running the ML software at 3 FPS. So with the camera and the projector FPS rates being the same it is possible to run for 5 minutes without any flicker at all. Looking at replacing the custom stepper controller with a cheap ebay unit.
The camera runs in RAW video mode at 1728x972 resolution. The RAW mode allows for many adjustments on the post. Thing like exposure, highlights, shadows etc.
Here is the resulting video.
https://drive.google.com/.../1yNSrdubdXCLXDXyKTkU.../view...

[Stuart Reid]

Damn you're a smart man Stan. I don't understand most of what you've done but I sure love seeing the results of your tinkering!

[Janice Glesser]

I second Stuart's comment above. Stan you are the MAN! I'm always intrigued by your projects and your posts. It is exciting to see what you can accomplish with your knowledge and perseverance. I wish you had been around when I was first getting into film transfers 😋

[Stan Jelavic]

Wow really appreciate your nice comments and support Stuart and Janice. I just try different things and try to keep my old brain working he he. Will have an update on the project using an inexpensive controller from ebay:
https://www.ebay.com/itm/175028855543
https://photos.app.goo.gl/eet8iSmrWHxSvWU78

[Stan Jelavic]

Managed to tune the system for zero jitter. The controller is programmed for 229 rpm which translates into 3FPS at the stepper with the "pulley ratio" taken into account. The camera is set for 3.010. Ran for 20 minutes (5400 frames) with absolutely no jitter. Some preliminary instructions are here (still updating):
https://github.com/vintagefilmograph..._video_capture

[Stan Jelavic]

Updated the github with lots of new info...
https://github.com/vintagefilmograph..._video_capture

[Stan Jelavic]

Figured out an easy way to sync the camera. Back it off and turn it away from the gate and point it to the cam (pulley). Adjust the speed control on the controller until the cam appears stationary. Actually it will jump up and down and possibly drift slowly. If the drift cannot be stopped by the speed control, then adjust the Magic Lantern Timer B to minimize the drift. Once done, refocus the camera back onto the gate. With this procedure I can run for several thousand frames without sync issues. It should be noted that the transport should be in good condition ensuring constant speed. It still may be possible that the drift catches up with you depending on the initial condition. In that case just run one step up for a few minutes if the drift is from the top, or one step down if the drift if coming from the bottom. Then switch back to the original speed. After that you can run for several thousand frames without sync issues.

[Stan Jelavic]

See my post at the top:
https://8mmforum.film-tech.com/vbb/f...sfer#post56188
Someone actually implemented a very similar version:
https://www.facebook.com/groups/4583...0002193642532/