Ben Ko

Ben Ko

I occasionally video runners with a GH2. I find that if i stick the camera on a tripod and photograph the runners coming towards me, the closer they get, the more their heads seem to "bobble" or wobble. I assume this is a variant of the jello-effect people write about when panning, except in this case i am not panning but the runner's are constantly moving forward and up and down. Anyway, any suggestions on how i can eliminate this? Thanks in advance for any advice.

JEL

JEL

Hey Ben :) (2-part reply)

This is the biggest mood-killer in modern low-budget film-making, in my opinion.

I don't know how pronounced the effect is on the GH2, but different CMOS cameras have different levels of it. I personally can't stand the effect of it and really hate the designer of this effect with all my guts.

The only real option is to buy a camera that doesn't use this, to be blunt, idiotic invention. So in other words; a CCD camera.

Personally I've given up making anything serious with a CMOS camera. It just looks like crap when you notice this 'wobble'. And with 1080p it gets even more pronounced because the chip is scanning a larger area. You can get away with standard-def stuff shot at 60fps, since that gives you the smallest scan-area and the fastest scan-speed. That's, in my opinion, the best way when using a CMOS camera. But ofcourse HD is what we're all after these days, so it's hardly a real option :)

JEL

JEL

Adobe premiere, and other packages, give you so called rolling shutter fixes. I've tried the one in CS6. I don't really like it. You can still see that a fix is going on. You can see distortions. It can work ok with vertical lines during pans, but with hand-held footage it falls short. Don't blame Adobe though, it's really an amazing tool. It's just that CMOS footage is already destroyed beyond realistic repair by the wobble.

The image-info you truly need to re-create the correct image is simply not recorded. That's the main problem with rolling shutter. And thus it's technically impossible to truly fix it.

Maybe in the future we will have computers that can create artificial info to replace the missing info. Such techniques can indeed do much good aesthetically (like the heal brush in photoshop), although not yet suitable for anything serious in my opinion

JEL

Jules Le Masson Fletcher

Jules Le Masson Fletcher

You are getting the "jello-effect", or properly called 'rolling shutter', because the sensor scans frames from top to bottom. And with fast moving objects, the sensor isn't scanning fast enough to capture that moving moment perfectly.
After Effects CS6 offers a great tool to fix it quick and easily. Also, after quick Google searching, you can easily find a number or different ways to fix it.

I provided two links with this reply, one video looks through Adobe's rolling shutter fixing tool and the other explains rolling shutter a little more in depth.

Hope this helps,
- Jules.

Links: adobe.ly/I8O1ri, vimeo.com/37316008

Ben Ko

Ben Ko

Thanks JEL and Jules for your feedback.

Googling for suggestions yields conflicting advice. Some say shoot with slower shutter as the increased blur will mask the shutter. Others (including link Jules points to) says shoot w/faster shutter. Still others say shutter speed and rolling shutter are independent. One site did say "shoot with shorter lenses". it's not always appropriate for the shot i want, but if it masks the rolling shutter problem, might be worth it. Haven't tried AE CS6 fix. I don;t look forward to applying the fix on every minute of footage i have. But will look into it.

Thanks again!

JEL

JEL

The Adobe rolling-shutter fix is best when you have footage with little to no relative movement.

For example, if you pan across a building-front or night skyline or stationary landscape or across an empty room. Stuff like that can sometimes be fixed with fair results.

Problems begin when you have relative movement in the frame; cars moving in one direction while you pan buildings in the opposite direction, or runners running toward you.

Slow shutter does indeed blur smaller issues on surfaces, but doesn't do much for problematic contrasty outlines (which your head-bobbing case would probably fall under. Their faces might look less skewed/distorted, but their head-shape might still be noticeably stretched/compressed)

Shorter lenses (wide-angle) cover a wider area and thus movement in the frame is over a smaller area. But technically it's all about the speed of movement per pixel. A slow pan with a super-zoom is just as safe as a fast pan with a wide-angle.

JEL

JEL

The rolling-shutter is dependent on frame-rate, not shutter-speed. The faster the frame-rate, the faster the chip has to be scanned. Shutter-speed only affects how much light each single pixel is allowed to pick up per scan.

JEL

JEL

:)

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