Hi Everyone - I wanted to share my 35mm scanner with the Kinograph community. The kinograph project inspired me to do this.
I use a Moviola for my film transport and a Red Epic Dragon for capture via Tokina 100mm macro. Built a trigger box for the RED + Arduino Debouncer for accurate triggering. Also made custom switch triggered by the sound head shaft.
***I’m really interested in the software sound decoding. If anyone can point me in the right direction that would be amazing.
If you have any questions or would like more detailed pictures of my setup let me know.
Here’s my first test scan with the A.I trailer (not stabilized)
Note: It’s normal for this trailer to go from 4 perfs 4:3 to 1:85 on FX shots because they did the FX @2K https://vimeo.com/138703634
Password: 35mm
Very nice, Robino. When the RED One first came out, I approached RED with a similar idea, but they weren’t interested, and I didn’t have the engeneering know-how to do it on my own. Well done!
As to registering the sprocket holes; remember that it is not always possible to recognize where a frame starts, as the edges are often black. There can also be copied in instabilities and gate size changes.
As to having a fixed rotation length - remember that film does shrink, and often unevenly (also because a roll of film can consist of various types and batches of film stock).
As to registering the sprocket holes visually, you might want to look into an IR sensor. The Scanity has a seperate camera that scans just the sprocket holes with infrared and then calculates the correct positioning on the fly.
It is important to take into account that sprocket holes can be damages, torn or even non existent.
For stabilisation afterwards it is important to scan as much of the frame as possible, preferably parts of the previous and following picture and as much of the sprocket holes as possible.
I like this…while I’m not up to speed technically quite yet, couldn’t we build something that counts sprocket holes that isn’t a sprocket? I too worry about film shrink and this not being “quite right” with certain films…and not wanting to do harm to them.
That said, I think you could easily enough use a photocell or laser to simply count each hole as it goes by in the floating gate, and in the same manner, tell the flash and shutter to fire. Of course, this idea won’t even work if the film is missing sprocket holes. So maybe a frame counter?
Or am I crazy? Or was this already suggested above and I missed it?
Please excuse my ignorance - I am a digital film maker and have never worked with film, but aren’t you reinventing the wheel?
Hasn’t the problem been solved by projectors?
Otherwise the image would creep up or down the wall as the movie progressed.
So, why don’t you just repeat their mechanics - with a digital mechanism instead of a mechanical one.
That link shows how an old school projector moves the film based on the holes, therefore every frame is always centred.
Instead of the purely mechanical process you could use two servos, one to insert a pin into the hole, and the other to move it along one or two holes distance exactly every time.
Once you have the amplitude of distance between the leading edge of each hole, the image should stay in the same place of every picture.
Or have I made some ignorant assumptions?
EMW
Ps - this is a great project, please keep up the great work, our global history and culture needs it.
@robinojones looks great! Now if only we could get Moviolas for everyone! Personally I’d be thrilled just to see one.
@Martin_Weiss I did some testing while back with a RED on the Kinograph prototype and it worked great. We hacked the remote trigger cable and used its stop-motion features to create individual files for each frame. The software RED uses picked it up great and assembled the video for us no problem. Ideally, the Kinograph design would be able to take a variety of capture camera options so that it could be more flexible - and more affordable since you wouldn’t have to buy a whole new camera system if you already have one that works.
As @EMW points out, the mechanics are the same. Unfortunately, @EMW, manufacturing the moving parts necessary to maintain accurate intermittent motion is difficult and expensive. At least, that’s what my research has shown. Also, the claw or pin mechanism is considered by many to be dangerous when scanning old film. Although, you are correct in observing that projectors do a perfectly find job moving film. Many people have hacked projectors into scanners and it’s a very viable option if you have the know-how to hack one yourself.
Another way of transporting. When I was a programmer of mainframes (long, long ago) we worked with tape units. While mounting the tape was sucked into those long shafts bij underpressure. The tape had a blistertape on it to indicate the start of the readable/writeable section. The tape stayed in the shafts. There were sensors in the shaft to ensure that the loop was correct all the time. These sensors controlled the spindles. Speeds of several meters per second were possible.
A Geneva Drive driving the wheels with pins (maybe less dangerous)?
But I think it would be fixed to 1 type of film…
And there is maybe no garantee you need no digital tracking later.
And the Geneva Drive might wear out too quickly with 3D prints.
And but…
EDIT: OTOH it could solve the contrast problem with trigger time detection, as the Geneva Drive may be easier to mark for a photo cell?
In regards to the frame float issue when using a stepper motor, I do believe this can be completely compensated for in software. Basically, you accumulate the error as (in fractional steps) and always output the number of steps that minimizes that error. If it’s a geared stepper, it’s best if you can determine the exact gear ratio. I have tried this with a geared stepper that has a known fractional gear ratio. With error compensation, I can step the motor through thousands of revolutions and observe that the shaft stops at the exact same angle it started from.
That sounds like the approach used in the Pi telecine project. He set the camera to capture a bit outside of the image frame and then somehow compared the position of the current frame to the position of the edge of visible area. He then fed that back to the program to adjust how far the stepper motor should turn.
I’m guessing this is mostly an issue when using the motor to drive the take-up spool directly. If you had the motor moving the film across the gate, then you should be able to make fairly accurate predictions of how much to move the film, since the motor only needs to turn the amount of each frame. In that approach, though, I’m assuming you’d need separate motors to drive the take up and feed reels.
I’m hoping I may have chanced upon a topic that aligns well with the data points in this thread.
I recently wrote an email to Bill, who made the projection video, but no clue if he’ll actually repo d or not.
I also saw someone above joke about getting access to a moviola. Sadly, looks like most of those are in California.
On to my project/inquiry… it’s not exactly Kinoscope in nature.
I recently went to a garage sale a bought a few 35mm movie trailers from a fellow that owned a cinema in the 1980s. I’d love to find a way to play them (sure it would be easier to just pipe the tiles into YouTube but who likes easy?)
I did the eBay thing but 35mm cinema projectors are still a fortune. I do however have 3D printers at home, a local makerspace with laser cutter and even a small forge that might be able to produce lost PLA metal parts.
My issue is that Bill’s animations are all for 16mm and I have no clue how to come up with the specs for 35mm. I could either try his design for transport or the geneva mechanism. I’ve been searching instructables, thingiverse and grabcad etc… but haven’t come upon anything useful to date.
Does anyone here have any thoughts/recommendations for me? I have a good suspicion that this project should be very doable for me to get something simple projected against a wall at home.
Sounds like a fun project! I did some quick searching around for a portable 35mm projector because I swore Kodak used to make one, but all I found was the Pageant 16mm version.
The most difficult part will be the intermittent motion. Perhaps you could buy a gate on eBay that includes the gear train for that?
You could use the optics from a slide projector and maybe even the light bulb setup too.
It actually sounds like a pretty difficult project to me, but I’m hoping you keep at it so we can see what you come up with!
I’ve been looking at eBay myself but weight and distance usually play a big factor here. I may but a msall hand crank unit just to harvest the lens itself.
Does your own setup have an intermittent component or are you doing that in software with the motors?
As it stands, I do have quite a lot of extrusion sitting here but was a bit concerned about the overall expense in motors.
My setup does not have intermittent motion. I hope to detect the frames electronically or with computer vision and take very quick photographs as the film passes in front of the camera.
Motors are an expensive component! I have chosen these for my new design (which I hope to document more publicly in the coming weeks):
1x GPN9 for the capstan drive that pulls the film
2x GPN12 for the feed and take-up reels
