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07-21-2013, 09:42 AM   #1
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Jello effect on video

Hi,

I am new in this forum, but I have been reading it for a while. I am one step from buying the Pentax K30, which I think it's perfect for me. Reasonably good lens with the kit, weather sealed, outstanding still quality, compatibility with old lenses, etc

The only bad thing about the pentax is the poor video quality, which is not so important for me but I would like to use it as well. Basically the two disadvantages are: low bitrate and the unacceptable jello effect. But I have a question about the jello effect. Apparently only appears when image stabilization is on. Could someone please confirm that jello effect is only visible when video stabilization is on?

Jello effect


As you can see the video is absolutely unacceptable. While color and contrast are very good (thanks to the sensor), the jello effect makes the video look rubbish.

It is the only doubt about the camera. If jello effect is always there and it's so notorious I won't buy the camera.

Thanks in advance and if I finally buy the camera I will be an active user of the forum.

07-21-2013, 01:20 PM   #2
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Were you using SR (shake reduction)? By default it is turned on in movie mode. If you watch your video, you will notice that it is best when only the subject moves and not the camera. When the camera moves, nothing is fluid - I assume this is the 'jello effect' to which you are referring?

I am guessing during camera movement SR is trying to compensate and would recommend shooting video with SR turned off and using a tripod with a head rated for video - or at least a monopod with a steady hand.
07-21-2013, 01:42 PM   #3
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Thanks for the reply.

Although I don't own the camera yet and the video is not mine. I am just aware of the problem with SR and jello effect, which makes the sr totally useless as destroys the video quality due to the jello effect.

My question is, does the effect dissapear turning off the SR? I haven't seen any videos without the SR.

I would like to know first hand if anybody has tested it. It's the only thing I need to confirm before buying the camera
07-21-2013, 01:59 PM   #4
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The effect is caused by the rolling shutter technology that is common for most DLSRs when recording video. Avoiding vibrations reduces the effect, in other words - use a tripod designed for video use. As a side benefit SR can then be turned off.

I don't know if SR in itself adds jello effect; I'm tempted to think that it reduces the effect unless the vibrations are extreme (as they are on that sample video). Definitely something to test next time we review a camera.

07-21-2013, 02:02 PM   #5
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When panning with the SR on the sensor tries to counter every sweep you do multiple times in all directions. Olympus on the other hand seems to have a "smarter" implementation which senses the direction of panning and only stabilizes the other axis. Though rolling and circling movements as in the clip is super hard to stabilize like that too.

Every small compensation the SR makes is a a small quick movement and overdoing it will exaggerate the jello effect, that's mere physics.

Video guys seems to turn off SR and use a rig instead for maximum quality and only use SR for pretty static shots where only shake is the movement.
07-21-2013, 02:36 PM   #6
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Not jello. Jello causes leaning verticals with pans due to the CMOS sensor readout being scanned a line at a time rather than the whole sensor at a time. That jerking is obviously stabilisation having too much to do, it has to jerk to a fresh position once its range of compensation has been reached. Youtube videos done on DSLRs all look ropey to me but download an original camera file and they play much better, so YouTube itself must reduce quality. The few K-30 videos I've taken look smooth enough, nothing like this example in the slightest.
07-21-2013, 02:45 PM - 1 Like   #7
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The SR in video mode is very different with the K30 and K-01

With the K5 they use the actual mechnical SR you also use when photographing, however with the K30 and K-01 they don't.
The SR used in video with those camera is software based, they record "full sensor" and the crop it a bit to and move the crop around the sensor. Just put the camera on a tripod if you don't believe me and compare the image you see with live-view when photographing or when you are in movie mode.
Anyway this the cause of the jelly effect with SR.
07-21-2013, 02:48 PM   #8
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QuoteOriginally posted by Anvh Quote
The SR in video mode is very different with the K30 and K-01

With the K5 they use the actual mechnical SR you also use when photographing, however with the K30 and K-01 they don't.
The SR used in video with those camera is software based, they record "full sensor" and the crop it a bit to and move the crop around the sensor. Just put the camera on a tripod if you don't believe me and compare the image you see with live-view when photographing or when you are in movie mode.
Anyway this the cause of the jelly effect with SR.
Ah, great correction Anvh! I didn't realize they totally reworked it.

07-21-2013, 03:11 PM   #9
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QuoteOriginally posted by Anvh Quote
The SR in video mode is very different with the K30 and K-01

With the K5 they use the actual mechnical SR you also use when photographing, however with the K30 and K-01 they don't.
The SR used in video with those camera is software based, they record "full sensor" and the crop it a bit to and move the crop around the sensor. Just put the camera on a tripod if you don't believe me and compare the image you see with live-view when photographing or when you are in movie mode.
Anyway this the cause of the jelly effect with SR.
I believe this is also the case with Q. The image seems cropped in video mode.
07-21-2013, 03:45 PM   #10
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If video isn't important to you, then why would this influence your purchase? The K30 is first and foremost a still image camera, and is great for that purpose, video, to me, is a nice side trick, there if you need it, but not it's main purpose.
If video is that important to you, I say buy a video camera instead, most can make still shots from the video, but they're not as good as from a still camera.

The point here is: there are trade offs to any "multi function" device, it can usually only do one thing great, the others only fair.

I don't expect my phone camera to produce images nearly as well as my DSLR's, nor do I expect my still camera to shoot great videos!

But that's just my opinion, I could be wrong!
07-21-2013, 04:47 PM   #11
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QuoteOriginally posted by crewl1 Quote
I believe this is also the case with Q. The image seems cropped in video mode.
Could very well be, they also do it with their compact camera's.
07-21-2013, 06:50 PM   #12
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QuoteOriginally posted by JohnnyXD Quote
Hi,

I am new in this forum, but I have been reading it for a while. I am one step from buying the Pentax K30, which I think it's perfect for me. Reasonably good lens with the kit, weather sealed, outstanding still quality, compatibility with old lenses, etc

The only bad thing about the pentax is the poor video quality, which is not so important for me but I would like to use it as well. Basically the two disadvantages are: low bitrate and the unacceptable jello effect. But I have a question about the jello effect. Apparently only appears when image stabilization is on. Could someone please confirm that jello effect is only visible when video stabilization is on?

Jello effect

PENTAX K30 16.2 MP with 18-135mm WR Lens - YouTube

As you can see the video is absolutely unacceptable. While color and contrast are very good (thanks to the sensor), the jello effect makes the video look rubbish.

It is the only doubt about the camera. If jello effect is always there and it's so notorious I won't buy the camera.

Thanks in advance and if I finally buy the camera I will be an active user of the forum.
The simple answer is yes. The jello effect will effectively disappear on the K-30/K-01 if you choose not to use SR. I think the audio problem is slightly more significant. Not only does the bitrate effectively limit audio to 11k at the high end of the audio spectrum, but a greater detriment is the aggressive AGC that raises the sound floor prominently in silent passages. If the audio track is important in terms of fidelity - it can only benefit you in terms of providing reference points (which, honestly, is true for all dSLR audio - but undeniably so for Pentax).
07-22-2013, 04:40 AM   #13
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So I can confirm that the jello effect is gone when SR is not activated? When you desactivate the SR, is the video still cropped?

Why everyone that uploads a video with the K30 does it with the SR activated???? It's terribly ugly!

PS: Even though I will use it for still image I expect it to have a decent video as well. Sound is not important at all.
07-22-2013, 10:40 AM   #14
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Yes the image is still cropped with video with SR off.
07-22-2013, 12:51 PM   #15
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So... as I can conclude from your comments.

- Jello effect only appears when SR on and the camera crops the video
- With SR off jello effect dissappears but the crop remains
- Quality is fairly good though there is not mic and the bitrate and the image is cropped

The question now is: how cropped is the image?

I will use it primarily for still, and I have no questions about it from now. Video is the only thing I have questions about because nobody seems to use it for video.

And has any of you tried first hand the difference between sr on and off and say, having checked it on the computer that jello effect is gone?

Since I am going to buy it online, I don't want any surprises

Thank you all for your help!
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