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Chris D Walker

Real-time Lapse

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This will be my first post so I would like to thank anyone who does read and maybe respond.


For more than a few months I've been playing with the idea of creating a time-lapse effect in-camera at 24 fps. The idea came from the Technicolor process that used a beam splitter to create separate red, green and blue images. Using three rolls of film attaining their image from one lens via a beam splitter it would be possible to create exposures of 1/16th of a second long. While I have not fully run the math a DP would also have an additional stop of light striking the negative, taking into account a loss of light whilst traveling through the beam splitter.


The first roll would carry the 'A' frames that are 1, 4, 7, 10, 13, 16, 19 & 22; the second roll would carry the 'B' frames that are 2, 5, 8, 11, 14, 17, 20 & 23, and the third roll would carry the 'C' frames that are 3, 6, 9, 12, 15, 18, 21 & 24. I imagine the only way to join them as one whole continuous motion would be after they've been telecined.


One interesting consideration would be that the long-exposed frames would 'bleed' into the following frames. There are also a number of problems mostly regarding how to synchronize the three rolls of film perfectly. It may be a better idea to use three CCD's on a special digital camera rather than use film.


Below is an attachment that can help visualize how the system could work.


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I'm not sure what the point of your idea is. Could you explain what you hope to achieve?


I could imagine this camera effect as a means of translating the sensation of nausea or delerium felt by a character in a narrative film; it could also be used to great effect in an experimental film. I grant that its uses are most likely limited but my curiosity is to see how something like this would appear on screen at 24 frames. I suppose it's what can be imagined by a director that presents the limits of something such as this.

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How would you exhibit this? Three rolls exhibited at once is pretty non-standard. If you were to just digitally comp them together, I think you would get an effect very close to step-printing (in that you have normal-speed motion with longer exposures) which is much simpler to do in all respects.

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It seems that you envisage taking a normal 24 frame event, splitting it into 3 8 frame pieces, and then reintegrating them overlapping each other. According to your diagram this would create an event lasting slightly more than 8 frames. Played back at 24 fps, this would reduce the 1 sec event to around 1/3 second, so the action would appear speeded up. There might also be some unusual visual aspects due to the overlapping frames, but at 24fps persistence of vision does a good job of smoothing over differences. I would imagine that what you propose is not greatly different to projecting 24fps material at 72fps.

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As I understand it, the idea is to print the frames in the order given as "Real Frame" numbers. In that case, shown at 24 fps, you'd have real speed action.


The difference is that you'd have a much larger effective shutter angle. If each 8 fps movement had a 180 degree shutter, the net effect would be 3 x 180 = 540 degrees. Objects in motion would have overlapping motion blur from frame to frame.


With very special exceptions, film camera shutters don't get much wider than roughly 180 degrees. But there are digital cameras that can give you very close to 360 degrees. You might compare the 180 and 360 settings on one of those cameras, this would just take you farther in the same direction.


360 degree motion blur looks like too much to most of us. It does have one interesting and useful effect: You can pan or tilt at any speed, there's never any skipping effect. It just goes to blur.




-- J.S.

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It's difficult to put into words and the diagram is completely clear.


My intent for the system would be to playback at 24 frames without speeding the motion up. The playback sequence would be A1, then B1 and then C1; the sequence would then be A2, B2 & C3.


A1: Exposes from 1/24 for 1/8th of a second.

B1: Exposes from 2/24 for 1/8th of a second.

C1: Exposes from 3/24 for 1/8th of a second etc.


The effect would be that the frames would contain motion artifacts from the preceding frame but also the following frame, thereby creating a fluidity in the movement of the camera or in the scene. Since this hasn't been seen before it is hard to imagine what a real-lapse film would look like. It would be hard work for someone to actually achieve this.

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