The basic idea is to move the 8mm film frame by frame with a stepper motor and take a picture of it. Afterwards putting the images together to a film.
The frames are quite small (abt 5x4mm) and in order to have a smooth playback of the film, the positioning and cropping of the images is critical.
After initial tests, I decided to use OpenCV for positioning and cropping.
While the hardware can deal with regular 8 and super 8, the software is still only supporting super 8.
First comparisons between a "professional copy" and the built here looks promising, but I believe that especially the camera settings still can be improved a lot.
Here a short video made with the scanner: (original from 1976)
The 3D print:
Originally I printed everything in PLA on my Ultimaker 2+. But after several hours of scanning I realised that the temperature of the stepper gets too high and some parts started deforming.
I printed the parts near the motor with ABS and that works just fine. (the stl files are sorted by material used)
Even that the 0.9 degree stepper usually positions the frames very precise, there are variations especially when glued parts of the film, which are thicker, pass by.
To ensure that the frames are always positioned in the middle of the cameras focus, I search for the contour on the left side - the sprocket hole in the film.
If that goes out of a certain tolerance, the stepper will readjust the frame.
After scanning all the frames, the software goes in another mode - calibration and crop.
A rectangular frame (the green one) is moved to the desired part of the frame. This is necessary because the frame position relative to the sprocket hole is camera specific.
After checking the right position of the rectangle with some random frames, the cropping is started with the push of a button. The frames are now cut out precisely and once done, they are put together with ffmpeg to a film.
This project is still ongoing - so what I'm working on:
1) still optimizing the film transportation. V1 works fine, but I want to get to less machine / film contact.
2) Optimize software: The individual parts (scanning, cropping, making the film) work fine independently, but I want to make the workflow in between smooth. (my intention is that it can be operated by anyone)
3) the camera settings: this is the part I still struggle a bit. I need to find the best settings for white balance and exposure. Will post my experiments in the log - any help would be highly appreciated. :)
4) add a post processing feature: Old cameras did not have picture stabilization. I ran one scanned film though the final cut pro stabilization and the result was amazing. But in order for FCP to stabilize, it needs to crop the frame a bit further. So what I plan is to have the choice to crop the frames exact (as now) or a bit wider, so that you don't loose any parts of the frames during post processing with 3rd party software
5) add regular 8 support: The sprocket wheel diameter and the number of sprockets are already optimized, so the film can be transported correctly. Whats missing is the adaptation of the software. (The sprocket holes are in different positions vs super 8). Not a big deal, but only makes sense once point 2 and 3 are done.