Jello...Jello?

Polanski

Polanski

Well-known member
Please, pardon my ignorance, but I have seen the word "jello" many times talking about video... What's the exact meaning in this context?

Thanks
 
"Jello" is usually referred to the skew/wobble issues with a CMOS sensor's rolling shutter. When you pan on a vertical line, it tends to look like its leaning, then when you stop, it giggles back into place. Kinda looks like Jello.

Heres an article that better explains the issues of CMOS sensors and how they differ from CCD's: http://dvxuser.com/jason/CMOS-CCD/
 
So this means that one would most likely not hand hold alot while filming. So no 'clover field' for this puppy.
 
there's a real difference between skew and jello. the jello on the d90 makes the image look like a ripple in the water when image is too shaky or at long focal lengths...where as the skew is noticeable with almost all cmos chip cameras that if you pan fast enough straight lines go sideways.
 
With smooth pans on a tripod I noticed the skew where it looked like it was freezing/grabbing some pixels, but on handheld there is a very noticeable jello jiggle wobble to the image. You can take steps to reduce it of course with rigs, shoulder mounts, weights etc, but if you're going straight hand held you're probably going to get a jiggle or two no matter how careful you are.
 
The image sensitivity, if you will, in the D90 is pretty extreme. Unless you steady it completely it will show an image that looks to be sort of underwater. Wobbling like "jello". Take a look at the videos done with the D90 on vimeo and you can practically see some examples in most of them. I know from experience because I own one.
 
Stabilizing the camera will help get rid of some jello, of course, but not necessarily all of it. Movement in the frame (whether movement of the camera, or movement of the subject) can cause the jello. Handheld motion is usually a good way to show the jello, because it becomes most prevalent when motion is reversed - i.e., moving one way and then suddenly moving the other. Vibration is the worst for showing jello because it consists of a lot of high-frequency motion in the image. You wouldn't want to mount a D90 or 5D MK II on a bicycle and shoot footage while riding down a rough road, or hard-mount an Aiptek "Go" to a helicopter or bolt it to the handlebars of a Harley. The resulting footage would be unwatchable -- unless you were doing it for a special jello effect...
 
Bolting the camera to something, even if that thing shakes, typically doesn't mean as much image shake as you may think since there's only lateral movement, no panning or tilting. With a wide angle lens and the subject lets say 2 meters away shaking the camera several cm up and down only means a few lines in the image, whereas a rather small shake presented as a tilt in handheld can mean half the image. There's a limit to everything of course but don't be afraid to try it. (This is also the principle behind the steadicam btw) /matt
 
I've seen video of both the D90 and the Mark II attached the bikes with no noticeable 'jello'. Here is a low res video I found: http://www.youtube.com/watch?v=M5DD0QaMUKA (There probably is some 'jello' in this youtube clilp, the res is just so low that you can't tell. But if you were doing a project, it would still be possible to get a POV on a bike or something with a D90; just maybe easier with a smaller camera)

There is a 5D Mark II promo video of it attached to the bike in high res. I just forget what country it was promo for...(?)
 
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