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    #21
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    Interesting. I'll try the Letus35 on the HV20 and see if it exhibits similar issues.


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    #22
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    has anybody called canon about the wobble thing ?

    i was speaking to canon repair (irvine,CA) this AM about another camera (hot pixels) ..
    i asked him about the hv20 and the wobble issue and he says this is the 1st he's heard about it ( also he's never worked on a hv20 yet) .. he asked other repair persons and said they haven't heard of it ... so now they heard of it at least once but if nobody else complains i don't think they will be any solutions ...


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    #23
    Senior Member Zim's Avatar
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    Nikon said the same thing about banding on the D200. They finally said it was normal.
    But I think the fixed it.


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    #24
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    Quote Originally Posted by donatello
    has anybody called canon about the wobble thing ?

    i was speaking to canon repair (irvine,CA) this AM about another camera (hot pixels) ..
    i asked him about the hv20 and the wobble issue and he says this is the 1st he's heard about it ( also he's never worked on a hv20 yet) .. he asked other repair persons and said they haven't heard of it ... so now they heard of it at least once but if nobody else complains i don't think they will be any solutions ...
    as you'll recall, what's causing the problem is the simultaneous readout of one part of the sensor while another part is being exposed. it's cheapest in hardware cost to allow ONE line at a time to build up charge in a time related to the chosen shutter speed and then pump it out to the next stage in the image processing. that will give you rolling shutter distortion on some types of motion. the sensor produces data at the rate of one sensor image per 1/24th of a second with bursts of one line at a time. it always produces data at this rate. if it didn't, then you could get rid of the problem by using a faster shutter speed.

    the most expensive thing to do in hardware is allow the ENTIRE sensor to build up charge in a time related to the chosen shutter speed and then pump that out to the next stage in the pipeline. the problem here is that it takes a lot of extra buffering space and control logic to do that. there are solutions in between, conceivably, where you buffer more than one line of the image at a time but you'd get probably wierder more blocky artifacts than using a single line.

    no matter how you look at it, if you're doing the simple thing, which it looks like the hv20 is doing, you're not going to solve this problem actually at all without using completely new hardware. it's akin to expecting your dslr to be "fixed" to shoot at 24fps continuously instead of whatever it does (say 2fps). the hardware to clock out all those bits and buffer them is just not there (though this is slightly different because here you'd want to change the continuous rate not the instantaneous rate).

    i have this camera. and it's annoying that it uses a rolling shutter of the least buffered kind. the camera is still very useful for most of the shooting i'd be doing though. and it's funny i had it for two months before i even noticed this as a general problem because i always use a steadicam whenever i move the camera. i only noticed it becasue i had shot some garbage footage without any stabilizer. the problem to me seems worse in cinemode (whcih i actually did notice originally).

    thre are other major and much more expensive cameras which have a similar problem. one of the cameras had noticeable warping in their demo footage shown publically: worse than on the footage released to the web (you have to go frame by frame to notice it in that footage).


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    #25
    Senior Member Ian-T's Avatar
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    Yes, it's annoying when this sort of thing happens but as I mentioned in another thread it just forces me to change my filming habits. It does not happen all of the time and like you I never even noticed it until people started talking about it. But it is definately a good lesson learned. Now I look for it when filming and do everything I can to avoid it. The rolling shutter effect in this cam is like what kryptonite is to superman. If you do what you can to avoid it then it stands as a super performing camcorder.


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    #26
    Senior Member Norbert's Avatar
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    I'm with Barry. If Sony can keep their CMOS cameras from producing a wobbling image, then why not Canon?
    DVX100AE owner between 10th Feb 2006 - 25th Oct 2006.
    Currently awaiting the [insert new camera here] firmware hack.


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    #27
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    Quote Originally Posted by Barry_Green
    It happens in my car stuff too. Much worse on full telephoto, but noticeable at full wide angle, with OIS on or off.

    Right now, until someone proves otherwise, as far as I'm concerned CMOS + rolling shutter + 24p = useless for moving shots. Looks fantastic for locked-down shots, but anything with vibration in it, it completely falls apart.
    But Stu over at his ProLost blog suggests that the HV20 must be locked down to a 1/48 shutter speed for best results. Is this horrible warbling of the image only visible with the high (you say 1/250+) shutter speeds?


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    #28
    Senior Member Norbert's Avatar
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    It seems that Sony's cameras also suffer from wobbling. Take a look at this: http://www.sonyhdvinfo.com/showthread.php?t=5664
    I will take the liberty to quote divergent from that thread:

    Quote Originally Posted by divergent
    Any vertical movement is going to result in the top of the frame recording a slightly different angle of view than the bottom of the frame - this results in each field image being slightly stretched or compressed vertically relative to the same shot from a static camera. So as the camera tilts up the image is compressed, and as it tilts down the image is stretched - if it is wobbling up and down (i.e. typical handheld footage) the image will alternate between stretched and compressed creating the "rubbery" effect.
    I think that sounds like a fair explanation of the HV20's behavior. My home made stabilizer (similar to a figrig) did not reduce much vertical movement so that could be a reasonable explanation to why my stabilizer didn't do any good.
    Next I would like to quote Laurence Kingston from the same thread:

    Quote Originally Posted by Laurence Kingston
    I got myself a Spiderbrace 2 from spiderbrace.com and the problem is fixed.
    Has anyone tried something like this with the HV20? If that is all it takes then I'm buying another HV20.
    Last edited by Norbert; 06-03-2007 at 04:47 AM.
    DVX100AE owner between 10th Feb 2006 - 25th Oct 2006.
    Currently awaiting the [insert new camera here] firmware hack.


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    #29
    Cross-Examiner Emanuel's Avatar
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    Quote Originally Posted by Norbert
    My home made stabilizer (similar to a figrig) did not reduce much vertical movement so that could be a reasonable explanation to why my stabilizer didn't do any good.
    I'd bet on that!

    Quote Originally Posted by sean90291
    But Stu over at his ProLost blog suggests that the HV20 must be locked down to a 1/48 shutter speed for best results. Is this horrible warbling of the image only visible with the high (you say 1/250+) shutter speeds?
    I have no my unit yet (quite busy on location) but I'm sure that's the point.

    And if you want to go with motion, try the 1/24th or 1/25th* of a second shutter and you should be fine with the motion blur, avoiding it with an effective camera movement handling:

    All the grip personnel knows that a camera movement goes to an end (where the HV20 can shine! -- the motion blur is a minor hassle and its annoying effect can be surpassed by opposition on contrary effect**). The problem is the most part of the prosumer shooters don't shoot as a professional grip nor thinks the shooting plan as an efficient director would/should do (I'm sorry...but I should say: truly professional, where the amateurism may be away).

    * 1/25@25p clip [ LINK ]

    ** Any psychologist can explain this, better than I, but the perception stuff is a subject of this business indeed, right?
    RED ONE @home
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    Emanuel & Co's RED ONE
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    RED ZOOM LENSES
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    Who am I?

    * LINK *
    ** IMDb **


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    #30
    Senior Member vsansal's Avatar
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    Quote Originally Posted by Barry_Green
    Interesting. I'll try the Letus35 on the HV20 and see if it exhibits similar issues.
    Barry, could you be able to test it?


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