by Klaas Robers » Thu Oct 23, 2014 7:39 pm
I remember that in the far past, I adapted an "Arriflex" 16 mm camera to run synchronously to the 625 lines TV-sync. This camera had a silvered 180 degrees shutter, so it was open for almost 50% of the time, in which time the film was exposed. In the other 50% the film was transported to the next frame, while the reflection on the shutter's back side was visible in the optical viewfinder. This is comparable to the well known mirror reflex photo camera, where the viewfinder image is also interrupted when the photo is taken.
The Arriflex had a DC-motor of which the speed could be controlled very easily. We made a kind of PLL with the TV frame sync such that the even frames were exposed on the film and the odd frames were viewfindered. After some experimenting a film could be taken off the sreen of a TV monitor without any visible artifacts, and that was the aim of this action. I think that we filmed experiments of the VLP (Video Long Play) in the research and development phase. May be that these films are still present in the Philips Research archieves. At that time (mid 70's) no other way existed to store these TV pictures in a safe way.
Now with CCD cameras these problems are coming back.
Edit later:
The Arriflex had a flash synchronisation contact. A special stroboscope could be used to illuminate the scene in a stroboscopic way. Thus no movement unsharpness would be seen in the film. We used that contact to measure the phase difference compared to the frame sync of the TV system, and keep that contstant. I remember that a small black bar was visible in the optical view finder. By trial and error we knew where the bar should be positioned to get a well exposed film off the TV screen.