General question about frame rates.

[Nick Ghent]

I know to obtain flicker free video you need to slow projection speed down to 16.66 fps to record on a digital camera with shutter speed set at 50fps.
is it possible to project a silent super 8mm film on a sound projector at 24fps as I can capture at 24fps on my camera, and then adjust the speed in post processing. Would this give me flicker free images, or am I missing something obvious? That is assuming I can project silent film at 24fps, I have never used a sound projector so don't know if that is in fact possible.
Thanks, Nick.

[Mark Mander]

Nick, if you can adjust the shutter speed on the camera you would need to slow the shutter, this will eliminate the flicker even at 24fps, Mark

[Nick Ghent]

So even if the projector was projecting at 24fps and my shutter speed on my camera was set at 24fps, I would still see flicker?

[Stan Jelavic]

Probably you would see it. Depending n the number of blades that you have, exposure on the camera, accuracy of you projector speed. The camera exposure has to hit the area between the blades blanking the image and away from the movie transport interval. So it is a hit an miss and even it you are lucky enough to get the perfect sync it may drift away after a while depending on the projector speed accuracy. It is better to have a projector speed set so that the fps is a submultiple of the camera fps. You get better timing margin.

[Nantawat Kittiwarakul]

Short answer - definitely YES.

Long answer - if you can match the camera's frame rate to projector's frame rate, it will probably work (at least to a certain degree).
The bitter truth is that today's camera sensor is of CMOS type, which is much more prone to speed difference/variation than of those older CCD sensor. On CMOS camera you'll get distinct horizontal bar slowly crawling up/down instead of (mostly barely noticeable) flicker as on CCD camera.

The only way to alleviate this phenomenon I can think of is to use lowest possible shutter speed - 1/24 second in this case. That should at least help averaging out that speed mismatch and make that bar less noticeable.

[Stan Jelavic]

Did a timing diagram.


The diagram assumes 3 blades. As you can see the blue rectangle (camera exposure) would have to be much below 6ms to have a chance of catching the white area. Suggestion. Remove the blades. You will have a nice window of 30ms and it may work then. Good luck.

[Lee Mannering]

Hello Nick
In the late 70s I used a video camera and modified a Super 8 projector to 2 blade shutter to effect a flicker less 24fps transfer. I still have those old tapes but of course scanned the same films since for a better result.