Wobbly image?

I looked at the clip, in a couple places the "problem" still exists (it's not a problem though, it's really an inherent attribute of CMOS sensors without global shutters), but the 1/25th of a second shutter has created more motion blur so that you can't see the "wobble" as clearly.

The reason the image get's "jelly-like" to you is because it's remaining in sharp focus, i.e., no motion blur, despite moving on the screen. So you see a sharp skew. Decreasing the shutter speed causes more motion blur which in-turn hides the skew for the most part, because instead of a clear, sharp image "wobbling", you're getting blur on the screen-you won't see the slanted edges because they, and the rest of the scene, will have motion blur instead.
 
Ah, thanks Jason for that explanation. I always did my tests with 1/50 shutter speed. I think I tried 1/25 one time though but to my eye it still wobbled. I also tried shooting DV with the HV20, which did not wobble like that. So, doesn't the problem with rolling shutter and CMOS affect the footage (as much) in lower resolutions?

Anyhow, I want to be able to shoot HDV at a 1/50 shutter speed without wobbles so I have decided to not let them send me a new HV20. I want my money back so I can instead save up for a camera that doesn't have rolling shutter and CMOS, if that is indeed what's causing the problem. I just couldn't have the image behave like that.
 
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I was at bestbuy doing some tests today. This problem is definitely not only limited to PAL units. NTSC unit has it as well. When I start shaking the camcorder slowly image started squishing/stretching. It was just like the clips I saw in this thread. There was a JVC HD7 right next to HV20. I did the same thing and the result was nothing like HV20. Then I switched the HV20 to 60i from 24p and the result was very pleasing. The squishing/stretching thing was nearly gone. I don't know how it is related to 24p but 60i doesn't seem to produce disturbing wobbly images.
 
Jason Rodriguez said:
I looked at the clip, in a couple places the "problem" still exists (it's not a problem though, it's really an inherent attribute of CMOS sensors without global shutters), but the 1/25th of a second shutter has created more motion blur so that you can't see the "wobble" as clearly.

The reason the image get's "jelly-like" to you is because it's remaining in sharp focus, i.e., no motion blur, despite moving on the screen. So you see a sharp skew. Decreasing the shutter speed causes more motion blur which in-turn hides the skew for the most part, because instead of a clear, sharp image "wobbling", you're getting blur on the screen-you won't see the slanted edges because they, and the rest of the scene, will have motion blur instead.
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Thank you Jason again. Quite useful your explanation.

So, can I infer the slow shutter speed can solve the problem (at least to my eyes -- I can not understand your reservations Zim) from the motion blur effect?
 
Have anybody taken this problem to the big guy Canon ? I mean, it's kind of a problem and i think they need to know about this problem so maybye they can fix it...
 
I'll have to inform you guys that I called just now and told them to not send me a new camera. Stupid, I know, but I didn't want to go through the hassle of sending another camera back. After discussing this problem here and on hv20.com I am fairly confident that this was not just one defective unit.

However, I will follow the development of the HV20 to see if Canon can fix this problem. So far I don't think Canon even knows about these discussions? I agree with Tomtebo. Someone should have a nice chat with Canon. If Canon then says that the camera is supposed to behave like this, then we can all base our decision on that and either buy the camera for what it is or just not buy the camera if you can't live with the wobbling.
 
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Norbert said:
If Canon then says that the camera is supposed to behave like this, then we can all base our decision on that and either buy the camera for what it is or just not buy the camera if you can't live with the wobbling.
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Ron, I understand you. But my bet would/will be to know how to live with this. As I said, unfortunately Canon have no "Barry Greens" to give support for their potential customers. Jason has given a good help to. At least, in order to understand what's happening there. Maybe he or Barry may give some hint on how to surpass the hassle. Barry gave an useful help on the gain issue.
 
Rolling shutter isn't going away anytime soon . . . this is the nature of CMOS architectures that don't have a series of charge storage transistors on the pixel (so they can't read-out and capture light at the same time like you can with a FIT CCD).

The extra transistors per pixel needed for charge storage so that you can have a true snap-shot shutter (which means on the chip you are able to store and read-out charge at the same time that you are also integrating) gives you less fill factor, which creates less dynamic range for a given pixel size, and also contributes to more fixed pattern noise and photo-response-non-uniformity (PRNU). So it's a lose-lose situation. There are CMOS sensors out there that have global shutters, but they are typically large sensors with huge pixels to keep the light gathering ability very good despite the fact that they might have double the number of transistors per pixel as what is in a much simpler 3T APS system.
 
Emanuel said:
Thank you Jason again. Quite useful your explanation.

So, can I infer the slow shutter speed can solve the problem (at least to my eyes -- I can not understand your reservations Zim) from the motion blur effect?
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...

Well it is the same reservations others are having. Like you said it might have to be something to live with, but I would rather not deal with that problem. I've seen some awesome footage from the HV20, but I'll wait on for more info on the HV20....I haven't ruled it out yet.

The problem seems to be mostly in 24p ? If the camare is on a tripod does the problems go away?
 
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Zim said:
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Well it is the same reservations others are having. Like you said it might have to be something to live with, but I would rather not deal with that problem. I've seen some awesome footage from the HV20, but I'll wait on for more info on the HV20....I haven't ruled it out yet.

The problem seems to be mostly in 24p ? If the camare is on a tripod does the problems go away?
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Understood. I was just referring that 25p@1/25 clip, beyond the motion blur (it doesn't bother me so much...or even at all) -- it seems fine at my eyes. Doesn't it at yours?

However, I am like you, following the user reviews. I have here other people (customers of mine) doing the same. Unfortunately, Ron gave up from his HV20 try. He would be a good eye for the task. Maybe he may change of ideas -- who knows?

EDIT -- Here's a fine example of a HV20 clip flying with a Merlin:

LINK

For sure, I have no clue on the shooting specs...

...but since I've had some contact with Charles Papert S.O.C., I can try to send him an email in order to know something on that (+ shutter speed, etc). Or if eventually he may read this post, he may help us to find more on subject (I'll PM the link towards our discussion here).
 
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I have to say that was really good. Some of the footage I've seen could be they way people are downloading too. Thanks for that link.
 
You're welcome.

Zim said:
I have to say that was really good.
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Are you talking about this one from Charles Papert or that one too from the last page shot at 25p and 1/25th of a second shutter ?
 
I was talking about the clip from Charles Papert . Not sure about the other one. Is that the one going up the stairs with the stuffed animal in it? If so the download is really bad to my mac. WMV play pretty good, but some downloads are un watchable. Real jumpy and blurry.
 
It is this one too:
Emanuel said:
Posting that example:

LINK

25p@1/25 where the problem seems away.
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Blurry? Maybe a little bit but it doesn't bother me. Jumpy? Maybe from the playback and is that all?

I'm trying to figure out if the shutter speed is or not a good solution to handle with the rolling shutter.

Here is another PAL user complaining:
http://hv20.com/showpost.php?p=729&postcount=30

Perhaps Charles Papert can help us in order to know if the NTSC wil be or not better in terms of this issue.

According Jason, it shall be. He already gave us some lights on this.

My only doubt is if we can get a similar result working over the shutter speed. A little bit of motion blur can be not a ugly solution or am I wrong here?
 
I think using this mac I get video that is real jumpy. It starts and stops. Starts and stops. So it is probably not the source video.
 
For sure, it's not. I have the same problem from an old PC. But not on a 1GB RAM laptop where plays blurry but fairly smooth.

25p@1/25 seems a solution for handheld shooting from a proper stabilizer.
 
What I find weird about all of this is that I've seen many examples of shots done in the same circumstances that do not display the wobble distortion at all. I really don't know what to make of it. Until this wobble thing showed up I was like "wow! look at what this little camera can do! I've got to get me one of these!". Now I'm afraid I might end up with rubber band footage.
 
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