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Re: 60fps slowmotion at varrying speed without juddering?

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Ben BigelowRe: 60fps slowmotion at varrying speed without juddering?
by on May 6, 2012 at 7:17:34 am

So I might be totally wrong, in which case I would love your feedback. (I linked to another post you were commenting on, you know your stuff!)

Well...here is my logic:

The footage I'm working with are slow tracking shots of architectural exteriors that I shot with the DSLR attached to my car. I'm about 20 feet from the building, wide lens (18). When I say slow, the car is idling so an object takes about 10-20 seconds to move from the right side of the frame to the left. And the image is pretty high contrast with a good amount of detail (poles, signs, shopping carts, things with hard edges etc.)

So in the 30fps comp, when I'm time stretching at intervals that are not either 200% (60 slowed to 30) or 100% (60 playing every other frame), I'm getting judder similar sounding to the horizontal movement of a line across the fame that he talks about in the adobe post. Yes? No?

This quote sums it up: "The only speed where you'll get a nice solid line in every frame or field is one that is an exact multiple of the frame rate. IOW, 1 frame 1 pixel of movement, 1 frame 2 pixels of movement, and so on"

I think that is the issue combined with a cinematography issue that he also mentions: "One basic rule of thumb that almost always works is the "Seven Second Rule." If it takes 7 seconds for the key element in your scene to move from one side of the screen to the other your shot will probably work."

Does this make sense? I think I'm getting noticeable judder because of the type of imagery I'm using. If it were footage of a figure walking around in different directions or something less directional and constant, I don't think I would be having this trouble.

As I mentioned, I have to animate the speed over time between 200% stretch and 100%. I've resorted to playing with motion blurs, which so far I haven't gotten perfect. Is there another workflow you would suggest? Maybe use timewarp instead of time remapping? Real Smart Motion Blur?

Thanks for any input!!


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