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GH2 Stutter/Judder/Strobe issues discussion
  • 218 Replies sorted by
  • @_gl, I think you;ve hit the nail on the head! Your example with the pixel checkerboard is a fantastic demonstration of the problem. That whacky LCD pulsing is exactly what I've been seeing in the GH2 footage and calling "strobing". It also explains why the problem seems rather worse with the GH2 than with some other DSLRs- because of the GH2's sharpness and detail, the LCD pixels have to pulse that much more.

    I agree with you about disabling sharpness in-camera, if possible. Whatever gets us closer to the raw sensor data and bypasses the questionable built-in DSP is an improvement, IMO.

  • Guys, some patience.
    I hope to move to film modes and related settings within August if all will be good.
  • I use a three monitor setup with my NLE system. Two LG 20" 1920x1080 computer monitors and also have my 50" Samsung D6300 1080P set hooked up for video preview. Both computer monitors display motion issues. The Samsung TV set looks normal. Do not judge motion on just your computer monitors. I'm not saying this is definitive, but one needs to be aware of this.

    This topic seems to be normal for damn near every new video camera that gets released. There's always a discussion on judder and overall motion.
  • @bdegazio, yeah, basically the GH2 is just too sharp for it's own good : ). Seriously, it's easy to get addicted to sharpening, I was for a long time, but if you look at most cinema footage it's rarely as sharpened. That's why you don't often notice the LCD strobing there.

    Also if you think about it, sharpening doesn't add any new detail (just increases contrast around edges), so there's no point having it burned into the footage when you can do it in post with more control (except for convenience if you don't want to do it in post). Also the extra contrast it creates uses up more bit-rate for no real benefit. And the high-bitrate patches already give you a more detailed image. So it would be great if (eventually) sharpening could be defeated altogether.
  • Please delete if this is not helpful, but . . .

    the 14-140 kit lens "judders" very badly in video with the OIS (Image Stabilization) turned on. Could this be the issue?
  • Hey guys, I just wanted to update what I was told about GH2 footage I sent out to a friend of mine that does post production work. He works on a bunch of high end films and I think what he says is golden. I actually believe him more than my own eyes. So what he told me is that it is in fact a sharpening issue. At first he agreed with my description about the problem and still thinks there is an " odd feel " to the GH2 24fps. After looking at it frame by frame he decided that the sharpening being done internally was causing the problem and can be perceived differently by different people. Just like some people are annoyed by fluorescent lighting while others are not. Someone mentioned earlier the rainbow effect with DLP projectors which might be the right idea.

    I will say that in his first email he said the footage looked slower than 24fps but that was before he looked at it closely. I was told there may be a few things you can do to address this problem and that he will mess around with the footage when he gets some free time. Obviously, being able to reduce the sharpness would help but I'll wait to hear what he says and pass it along. A few other things that can have a negative affect were down rezzing and digital projection can highlight it as well. Their company actually fixed a film from China which had similar problems but for different reasons.

    This is still a problem for me and others, I believe. I do think that there is hope in fixing it. Now, I really respect this guy but take it for what its worth. I don't think he spent a ton of time looking into this. It looks like this thread was heading in this direction on it's own anyway.

  • @Dalefpf Thanks for the update. Will be great to see what else he comes up with.

    If it is a sharpening issue, what happens if you just shoot a bit out of focus on the GH2? If the judder goes away would that tell us anything at all? And if it doesn't, similarly, would that be revealing? Hell, I'll try it!
  • @Mark_the_Harp yep if the judder goes away, it's the sharpening/LCD issue. I never see my problem on unsharp areas. You can also try just blurring the image a little in post (same deal).
  • Shooting handheld reduces the sharpening as well. In smooth @ -2s with .9 ND I've not had much of a juddery stuttery problem in camera (just on my last gen. Imac which can't keep up in FCPX). But yeah, if we could reduce sharpening even more and turn down the ISO it'd be great. That ultra sharp HD look is, IMHO, very unappealing in comparison to film…and to be avoided if you want the cinematic look
  • @Mark_the_Harp I too have noticed what is being called judder (a staccato-like pattern on sharp edges and and regions of high contrast) in my footage with pan, tilt, and dolly movements. I believe sharpening contributes to the effect, for I have several pan and dolly shots with areas of soft focus that do not judder. It's only when the shot comes into focus does the judder occur. It also depends on the speed of the camera movement. Very slow movement does not seem to cause the effect, or at least it is less noticeable.

  • @_gl

    Blurring in post was my first suggestion which he said would be a start. From what I could understand was that it was something that the camera is doing that was screwing up the image as it's being recorded. Not sure what the difference would be. Maybe someone here would know. I'm going to pick his brain later in the week. Didn't want to annoy him too much.
  • A diffusion filter might be a better option than post-processing blurring. It doesn't degrade sharpness.
  • @stonebat, I was suggesting blurring as a test to id the problem, not as a solution (although careful blurring might work).

    re. diffuser, anything that lowers contrast (which a diffuser does) reduces sharpness, contrast = sharpness.
  • If sharpness is the issue than contrast plays a role too. The B&W video Ian-T posted as an example has high contrast, and high contrast strongly improves the 'perceived' sharpness. If we're on the right track, old soft and low contrast lenses should decrease the effect. If someone who owns such lenses (Canon FD maybe) could run a test against a kit lens or other sharp contrasty lens we might see if it really makes a difference.
  • @_gl I Yes a diffusion filter tames excessive sharpness... usually aliasing. That's a good thing while the filter retains non-aliased good details.

    24p might introduce more motion aliasing. A diffusion filter reduces such aliasing. That was lpowell's advice on aliasing topic thread from last year and I got a diffusion filter.
  • @chip it's best to test it on m43 lenses as they tend to give more aliasing.
  • >it's best to test it on m43 lenses as they tend to give more aliasing.

    yes, that's what I meant, run a test with one of those lenses against a low contrast, soft, old lens and see if it makes a difference to motion. I don't have a low contrast lens, else I'd do it myself.
  • I have a diffusion filter and 20.7 pancake. Let me see if I can run some test. Not sure how late I can stay awake nowadays.
  • Also, you may wish to experiment with slower shutter speeds with moving shots. I find a 1/30th shutter all but eliminates judder no matter what the speed of the pan. My initial impression is that 1/30th has a more "filmic" look in motion than 1/50th, even though it doesn't obey the 180 degree shutter rule.
  • Of course judder will always seem more on sharp contrast images!!!!
    This is due to you can actually see the edge of the moving image! When an image is out of focus, you do not see edges as well.... of course..

    I'm willing to bet if someone put up a 24P double blind test from two different cameras, one being the GH2, and the other something else, I doubt most of us would be able to tell the motion difference when comparing the footage.

    Of course, you would have to make sure everything was setup correctly. 24P and shutter speed of course have to be the same. Also, it would probably be smarter to compare in 720P since the GH2 probably looks better in 1080P then most of its competition.

  • I believe you guys got it right. I had the same feeling that the sharpness in the GH-2's image is what's causing this problem. I don't see it in the majority of clips I watch...but...I'm suprised no one said anything about the video Beuller posted recently. In that video watch the the fence in the wide open shots while the camera pans left to right quickly. It looks like Christmas lights. It's the same exact anomolly we see in the very last video I posted.

    B3Guy might also be hitting on a point. When using the kit lens with OIS turned on...I've always noticed the image is VERY sharp. Not sure if I see the same issues when using legacy lenses. But I'm hoping one of you chimes in with some sort of test to help us narrow this down. This might also explain why a lot of folks say the image from the kit lens look :-)
  • "a low contrast, soft, old lens" - there's, ahem, a few of those on EBay, starting at around $15. This is the brilliance for m4/3: a $20 Minolta MD adapter and the world is your oyster!
  • Ian_T, I think you're exactely right. I had a Pentax K-x once and it's video was a moire and aliasing mess. The kit lens that came with it was very sharp, one of the sharpest kit-lenses you could get. I popped on an old Porst 50mm 1.4 and it took away most of the moire mess, but at the same time it didn't render less detail. Detail stayed the exact same, the amount of artifical detail (aliasing) just decreased big time. GH2 still adds that artifical detail despite sharpness setting at -2, and the sharp kit-lenses seem to improve it further, making it look so digital.
    I do have old lenses but they're not low contrast or overly soft, I'd still like to know if that would improve motion compared to sharp, hifh contrast lenses (like panny's).
  • Further to "a low contrast, soft, old lens" @CobyD, I've been buying Canon FLs on ebay for some time now, and have almost the full set. With few exceptions they've been costing less than $100 each. A And, a local company has been able to fully service them. A 55mm f:1.2 makes a damn fine picture.