Tension on the film reel

[David Holt]

Hello everybody, names Dave.
I've been slowly (over 3 years) building a 8mm cine scanner. I finally got round to actually scanning some old film and noticed that when i transport the film sometimes theres a little drift and its not always in the same spot. My guess is that as the film reel is free running the looseness causes the film to not be taught. How would you suggest I add tension or friction to the film or reel?

[Stan Jelavic]

Hi David, I assume you are referring to jitter or film shake? If that is it then there are many postprocessing tools to fix that.
https://www.youtube.com/watch?v=GaPNf2Rk4qQ
Here is some more info on the script:
https://8mmforum.film-tech.com/vbb/f...4945#post24945
The film shake can be caused by several issues:
- worn out transport - reduced claw travel
- supply reel rewound too snug
- film width - film shrinkage etc
- some issues with takeup -- too much tension
Hope this helps.

[Nantawat Kittiwarakul]

Is it projector-based scanner? Any additional info and/or pics would be very helpful.

[David Holt]

Hi all, as you can see, i built a transportation device based on a flatbed scanner. My issue is that when i transport the film, even tho iv worked out the math so it only moves 6 frames, sometimes its slighty off which mean it cuts part of the frame off.

[Nantawat Kittiwarakul]

Ah, that's another completely different method than my approach. Therefore I'm unable to leave any comment for this.

Since I'm dead lazy and electronically idiot , so I chose this simple projector - camera setup instead (still frame-by-frame capture however). Seems to work perfectly fine to my need so I'd stick to this route.

[Stan Jelavic]

We all learn Nantawat and learn from each other. Here are a few thought from my side. From the pictures I assume the transport is done with a stepper of some sort connected to a cog pulley. This is different than using a claw. The cog wheel position has to be very precise so that is one thing to check. Possibly have another camera point it to the cog pulley and trigger it with the existing trigger mechanism. Then blow up the images from the camera and check for the position of the pulley. The other issue could be the long run from the "film gate" to the pulley. The longer the film the worse the impact of film stretch/shrinkage. I did a setup a while back with two projectors, one pulling the film and the other to take images. That did not work out well and the resulting video has lots of film share. So possibly move thee pulley as close as possible to the scanner. Are the scanned images of good quality?

[David Holt]

Hi Stan, thank you for your imput. I've actually spent the day moving my stepper as close as I can to the scanner. Which has improved stability of the scanned image. Scanned images are blury but that is because I have yet to make a film guide for the scanner, so the film sit 4mm above the scanner glass. But when I scan film on the glass it's perfect. I worked out that I can move 6 frames with my setup with integer steps. Anything more would cause drift as the steps would be not be whole numbers. Iv also decided to use a 2nd stepper with another gear on the scanners input side to try and hold the film steady. I'll left you know how I get on.

Dave.

[Stan Jelavic]

Looks like you are on the right track David. Yes, keep us posted please.

[Janice Glesser]

Hi David... I have read and seen other setups using a scanner before but not one as automated as yours. Like Stan I too am interested in seeing your progress and the resulting scans.

[Nantawat Kittiwarakul]

As Stan said, the longer length between the sprocket wheel & the actual scanning point, the more deviation it could be.

Guessing from the picture that distance would be at least some 12" apart. Even with only 1% shrinkage to the film that would translate to around 3 millimeters - about one frame height for Double 8 film. Gotta find ways to counteract this issue then.

[David Holt]

The only ways I know of to stableize the film is to move the stepper closer(which I've done) And to try and build a guide for the film on the scanner. But not having access to a 3d printer makes that I little difficult.

[Stan Jelavic]

The 3D printers are becoming pretty affordable. This is what I bought last year and been using it ever since. Very happy with it.
https://www.amazon.com/Pro-Removable...dp/B07GYRQVYV/

[David Holt]

As much as I'd love a 3d printer. I just can't warrent spending £150 on something I may only use once or twice. Especially this close to Christmas. What I might do is work out how to make the stl file and pay a service to print it for me.

[Stan Jelavic]

I could print it for you if you could take care of shipping costs.

[David Holt]

Do you have any idea how much it would cost to ship to the UK?