The Jell-O effect?

SLavictoire

SLavictoire

Well-known member
Hi there, When the last clip from Kanye West - All of the lights came out, some friends showed me what it look like because they were saying it was shoot with DSLR. At the start of the clip, with the little girl, a guy screamed out "look at that jell-o effect! It's real nice!" Later I asked him what was that Jell-O effect he mentionned before. Because I was new to DSRL footage. He answered that it was typic to DSLR shutters. My friend is right?

Here's the video if you never saw it.

 
The "Jell-O" effect is not just typical to DSLR. It's an artifact of CMOS image chips. These chips have a rolling shutter, as opposed to the global shutter of a CCD chip. Rolling shutter means that each frame is not refreshed all at once but in sequential pieces (the CCD's global shutter takes in all the information at once). This shows up mostly in vertical lines and on fast pans and other quick camera movements. You'll see the frame "wiggle" like a pile of Jell-O.

CMOS chips can make beautiful pictures, but you have to know how to shoot around its limitations.
 
For the sake of accurateness, rolling shutter is not just a CMOS or CCD issue, either design style can use a global or a rolling shutter. Granted, they typically are offered as you've indicated, that said, I've seen global shutter CMOS designs.

I've asked a few manufacturers why they won't do global shutter on CMOS and they said that while they gain the benefit of not having the rolling shutter issue, their are some disadvantages they didn't want to take the hit with. They wouldn't discuss, but I figured it was loss of more active area in each pixel for the extra circuitry for the CMOS global shutter implementation.

And even further, not all rolling shutters are equal as well. Use a Nikon D90, then a Canon 7D, then an AF100 and you can see the progression of how they all behave. (worst to best listed).
 
SLavictoire said:
What do you mean by that?
Click to expand...

I mean that fast camera moves and shaky hand-held ("Jason Bourne" style) and other similar things are a bit more restricted. It takes a little practice shooting with rolling shutter to figure out what works and what doesn't.
 
So, any DSLR got the rolling shutter? Is it including other cameras that are tapeless? If you says it's really the chip, I would choose a CCD. Is there any DSLR witch have a CCD chip? If it's an artifact in the CMOS chips, is it normal i'm not having that artifact in the HDR-FX7 from Sony, witch is using 3 CMOS chips? I'm starting to get a little confuse.

"EDIT"

Heres a good exemple : The NXCAM NEXFUS100K from Sony is considered has a DSLR since it got one 35mm CMOS chip? Do you think it will do the "Jell-O" effect if some was shooting with the Jason Bourne style?
 
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Every CMOS camera that has a rolling shutter, will exhibit the artifacts associated with rolling shutters. The Red One, the Red Epic, the GH2, the 7D, the EX1, the AF100, the 5D, all DSLRs on the market, etc.

The only question is to what degree they exhibit those artifacts. The Nikon D90 is very very very bad, and the Arri Alexa is nearly perfect. It still has it, but it's to such a minor degree that it's basically nonexistent.

There are categories of how good or bad the rolling shutter is. In the "pretty good" category you'll find the Red, the EX1, the AF100, the F3, and probably the FS100 but we won't know until it's tested. In the mediocre category you'll find most of the DSLRs, the GH2, and less expensive video cameras like the HV20. In the "awful" category are things like the Nikon D90.
 
Thanks Mr. Green, I got one last question, does the T2i have a descent artifact? And the shutter speed does affect this artifact?
 
Shutter speed has ZERO effect on the presence of rolling shutter artifacts. The rolling shutter effects will be equally visible regardles of what you set the shutter speed at.

The T2i is in the mediocre category for rolling shutter level. Not really bad, not very good, but most folks seem to find it workable.
 
Ok, so depending of what I'm going to shoot and how it will be done, the artifact will be there. And it will be worst if it's shoot the Jason Bourne style. Can it be corrected in post? By the way, thanks about the Shutter Speed, it was a good question I got in mind for quite some time.
 
The latest release of iMovie, I believe, has a plug-in for fixing rolling shutter artifact. It's not perfect. Impressive for what it does, but it's not perfect. Not sure what else is out there for other NLEs.

I shoot with a T2i, and don't have a problem. But then, I shoot to avoid the problem.
 
So, I shouldn't restrain myself for buying a T2i if I want to upgrade my gear? I don't have great budget, that's why I want to stick to a T2i. Now that i've got knowlegde about these artifact, I shall keep it in mind, when I'll get my self a DSLR
 
Sony Vegas 10 has a plugin built in to eliminate rolling shutter as well.
I've seen some tutorials to remove the effect in After Effects without any specific plugins, but it is time consuming and long rendering.

Seems most NLEs are geared up to handle this effect.
 
Do any of these plugins handle objects that are not leaning as opposed to backgrounds that are? I remember seeing some plugins that could identify this with a little help, but I never tried them. Think of tracking a moving object. If you move close to the speed of the object, it will not lean, but the background definitely will.
 
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