Suggestions for a Telecine at the Gate Set-up

[Brent Wohlberg]

Hey folks,
I am new to the game here. I am incorporating 8mm film transfers into my existing Vhs/slide/photo/ digitizing business..
I am trying my best to get the best quality film transfers to Digital. I am pretty happy with my existing set-up of capturing the projected film onto a small screen. I do have an issue with flickering at times, which I would love to get rid of. What I would really like to accomplish is a rock-solid set up that just captures at the film gate...and I guess I'd like to find some kind of Dimmable LED light..

Currently I am using an Elmo Sound ST-600 and a Panasonic Gh4


As a Side note, I am also wondering about buying into this system, does anyone have any experience with this company?
they are called Film-Digital https://en.film-digital.com/, and they do have interesting option here, but quite pricey..

Thanks!

Brent

[Nantawat Kittiwarakul]

What's missing from your setup is the optical part - the lens for "projecting" the image right into the camera's sensor (oh and the LED as the light source as well).

Otherwise it's more or less the same as what you already have - a modified projector and a camera with excellent video capability.

[Stan Jelavic]

Just wanted to add that they modify the projector for 16.66ms frame (60 FPS). So if you set your video recorder to 60 FPS you will get flickerless transfer.
https://en.film-digital.com/product-...-bauer-t502-n8
Plus they add the variable intensity LED. But the kit is pretty pricey.
Replacing the light in the projector with the LED is not that hard but I have not seen any telecine DIY "quartz" control motors. People generally implement a variable speed control or go frame-by-frame with a trigger signal.
I have some ideas how you can implement that. It involves a feedback from the claw mechanism into the motor controller.

[Brent Wohlberg]

Thanks Stan and Nantawat..
I was thinking about the below lens from the same company:

https://en.film-digital.com/product-...r-filmtransfer

Again, pretty expensive, but I can't think of any other alternative for my Gh4 to get full frame into the gate..

Stan: I don't think I can really do frame by frame because of the time it takes to do so. I actually bought a wolverine transfer device, and realized that it takes about 30minutes for a 50ft reel, which is not feasible for me, and I found the quality was in general worse than shooting it on white material with my Gh4..

I am wondering how I could modify my projector motor to the 16.66ms frame..Can you point me in the right direction on that one?

[Nantawat Kittiwarakul]

Once tried with my APS-C sensor sized camera - it is (OK dont laught) Sony NEX-5N. Using standard 50mm lens from another 16mm projector.
No serious modifications made, just adding an "iris" made of cardboard on the lens front to reduce some light output&gain some more depth of field. I didn't expect any miracle at all, just for fun - and the heck of it.

The result is, to be honest, surprisingly good. Edge-to-edge razor sharp&no vignette at all.

I was temped to go into this direction but due to its clumsiness I eventually didn't. Besides my camera doesn't like working in video mode for long period. Currently going in frame by frame setup with a camcorder instead.

Maybe I would consider this approach again in the future, maybe.

PS I might have the pic of that setup buried in my gallery somewhere. Might take time to find it.

[Stan Jelavic]

Brent, that lens is very expensive. There are some alternatives.
- Look at macro lenses for your camera. Looks like there is a 1:1 macro available. That would cover around 1/3 of your sensor. You could consider the extender ring or a few of them. Some macro lenses do not like that because you run beyond the lens operating range.
- Use a good quality c mount lens with an extender and adapter for your camera. This is essentially what film-digital do. There are some excellent C mount lenses out there. Check the Mattias posts in the Wolverine thread.


As far as the motor control I looked at some ideas a while back. 60 FPS sounds very high. What is the lowest frame rate that you can do with your camera or is 60 the only choice? Can your projector run this fast?
Possible alternatives. Run projector at an integer fraction of 60 such as 15 and then change the frame rate in the post.
Back to motor sync. Two approaches.
1. "quartz control" This does not use the feedback but ensures that the motor runs at a precise RPM. For this you need a stepper motor with with enough torque at 15x60 =900 RPM. The rpm has to be adjusted if the belt is used or gearing.
2. Feedback. Have optical sensor installed around the claw and feed it into an arduino or similar controller that drives the motor controller.
3. Use a powerful motor with the PWM controller.

Hope this helps. Let me know if you need more details.

[Nantawat Kittiwarakul]

Speaking about using stepper motor...

Is it possible to have it set at exact designated speed say, half the speed of camera's frame rate?

Just got an idea. Having the projector's shutter removed and motor replaced with stepper motor, running at exact (or as closest possible to) 50% of camera's frame rate. Each film frame will be then captured at least ONCE, mostly TWICE. So you'll always get at lease one "clean" frame captured no matter what.

Then using VirtualDub for example to extrace odd frame for one clip, even frame for another clip. The rest would be the job of editing program to chop out any blurry/ghosting frames from one clip, and replace it with clean frames from another clip.
(The less speed "drift", the less post-capture work of course.)

A tad more post-capture work, but no complicated servo-controlled circuitry work involved. And it runs at relatively decent speed (12.5fps in PAL land) while still safe enough for most films as well. Any camera at designated frame rate can be used also, making it pretty flexible.

Not idiot-proof approach, but not rocket science also. I might develop this idea further if I have the chance.

[Brian Fretwell]

Admittedly I did this a very long time ago with a tube camera. I adjusted the speed whilst viewing the picture on a monitor until the picture showed no strobing/brightness variations, of course the "lag" in the camera tube smoothed things out quite lot.

[Stan Jelavic]

The steppers can have pretty precise speed driven by the controller with xtal oscillator but there are a few issues to look at:
- The motor size (torque) has to be sufficient, otherwise it will start slipping.
- The steppers do not run at high RMP. Around 900 should be OK but I have not done much research on that.
That is assuming direct drive but many projectors use a belt drive requiring higher motor speeds.
Here are some specs:
https://www.orientalmotor.com/produc...s-AC_Input.pdf
https://www.orientalmotor.com/steppe...8aAvN8EALw_wcB

These curves show that the motor can go as high as 6000 rpm.

Some discussion on motor torque here:
https://forums.kinograph.cc/t/take-u...r-system/40/21

My quick calculation indicates that the torque at 900 rpm is marginal. Using the belt reduces the torque requirements but requires higher speed, but at higher speed the motor torque drops down so it is a tradeoff.

[Jacques P. Fontaine]

Hi Brent, sorry I'm so slow but here is a list of items I purchased on ebay for my conversion system;

1. SATCO S9499 6.5W LED MR16 LED 5000K 40' beam GU5.3 12V AC/DC

2. 2 Pack GU10 Base Halogen Bulb 120V 35W Light Bulb

3. Armour Products Etch Glass Etching Cream Compound 2.8 oz # 15-0150 New Sealed

4. Waterproof AC to DC 12V 10-150W Switch Power Supply Adapter LED Light Driver US

5. SUPERNIGHT® Aluminium Brightness Dimmer DC 12-24V 8A for Single Color LED Strip

6. Sylvania MR16-50-12 Mini Takedown Light Module 12V 50W With Socket and Bracket

7. EcoSmart MR16 GU5.3 50W 12V Bright White Dimmable LED Light Bulb 3Pk

If you would like pic's of how I modded my GL2500 dual 8 projector let me know and I will post here.

Also, would like to post a clip of recent 50+ year old super 8 I just finished using above for the first time

[Brian Fretwell]

I have not managed to get a GU10 lamp and base into any projector I have tried, it has been too long.

[Tom Fales]

Jacques
As to the lighting control dimmer module you are using, have you investigated or experimented with splicing into the projector lamp feed and inserting a dimmer control knob to control lighting levels to your lamp? That way you would not need a separate ac power converter, just a rotary dimmer switch assembly to install somewhere on the projector case.
Has anyone else experimented with this approach?
Thanks

[Brent Wohlberg]

Hey Jacques.. yes I am working on this right now.. will let you know how it works out..

[Erkki Tikkanen]

Stan wrote: "Just wanted to add that they modify the projector for 16.66ms frame (60 FPS). So if you set your video recorder to 60 FPS you will get flickerless transfer."

Actually, as Film-Digital is in Germany, 16.66 is meant for the PAL system, 3 times 16,66 is 50fps. In the USA you should use 20fps in your projector to get the same effect, 3 times 20 is 60fps. Then you get the flickerless video. This is only if you use a projector with 3 blades.

[Stan Jelavic]

Thanks for the correction Erkki. My bad.