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Bad strobing on YPbPr output

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Chris Babbitt
Bad strobing on YPbPr output
on Jul 24, 2008 at 5:07:31 am

For me, this whole transition from SD to HD and all it's various formats has been interesting, to say the least. Up until now, everything I have shot with my EX has been either 60p or 60i. Today, I experimented with 30p and 24p. I noticed a bit of what some call strobing in the viewfinder when panning, which I expected and didn't find objectionable. However, when I connected the camera to my HD monitor (both a 32" LCD and a 56" DLP) using the component cable, the pans look so bad, it's as though something is really wrong. I noticed that the YPbPr output on the camera is limited to 60p even though the footage was shot in 24 or 30p (page 117 of the manual). Could this be the reason why it looks so much worse on the monitor? It looks about the same in the clip browser as it looked while I was shooting, and the same in FCP as well, but it looks really bad when played back from the camera. Am I missing a setting somewhere?


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Don Greening
Re: Bad strobing on YPbPr output
on Jul 24, 2008 at 5:18:42 pm

[Chris Babbitt] "Am I missing a setting somewhere?"

Hi Chris,

What've you been setting your shutter speed at?

Can you post a sample clip somehow?

- Don



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Chris Babbitt
Re: Bad strobing on YPbPr output
on Jul 24, 2008 at 5:25:12 pm

Shutter speed is 1/60. I don't think posting a clip will help. As I said, it doesn't look bad on computer. It's only when playing out of the camera that the strobing looks really exaggerated.



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Don Greening
More Help please on Bad strobing on YPbPr output
on Jul 24, 2008 at 5:45:28 pm

Okay. Well, I'll be the first to admit that I haven't used any sort of external monitoring during a shoot so I can't offer any worthwhile suggestions. You've got the shutter set right: 1/60 sec. minimum for 30p and I'd suggest 1/48 sec. for 24p. I'm wondering if it's the refresh rate of the external monitor. It may be the way the camera is outputting to the monitor, although there's no adjustment there other than to simply activate the output from the camera menu.

I shoot 1080p 30 all the time and am quite pleased with the result. I've changed the subject title to attract more attention from our peers.

- Don


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Chris Babbitt
Re: More Help please on Bad strobing on YPbPr output
on Jul 24, 2008 at 6:24:39 pm

Do think it could have anything to do with the camera's output being 60p? I'm not sure if strobing is the correct term. Jitter might be more descriptive. For example, as I pan across a post, the post appears to move rapidly horizontally, like it's vibrating. And I'm talking about camera pans / moves. Same problem on two different monitors (consumer HDTVs).



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Don Greening
Re: More Help please on Bad strobing on YPbPr output
on Jul 24, 2008 at 6:49:40 pm

Now you've peaked my own curiosity. It's been awhile since I had my EX connected to my 50" plasma using composite but I don't remember any glaring issues with playback or panning. But I was playing back 30p and not 24p. If it looks decent with the computer playing back the footage then you'll have to trust that future EX recorded moves will also look good in the final product.

When I first started shooting progressive way back when with my XL2 I was rather disappointed with the EVF's playback (stuttering frames on panning) but once edited it looked fine and I wouldn't go back to shooting interlaced unless a client specifically requested it.

Chris, we just need to have others weigh in on this topic and share their experiences with using the EX hooked up to an external monitor during a shoot.

- Don


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Chris Babbitt
Re: More Help please on Bad strobing on YPbPr output
on Jul 24, 2008 at 7:28:02 pm

Yes, I think I just need to do some more testing under more actual shooting conditions, and not just panning stationary objects. I was just concerned that something may be wrong with the camera. For the time being, for paying gigs, I think I'll just stick to 60p.



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Don Greening
Re: More Help please on Bad strobing on YPbPr output
on Jul 24, 2008 at 7:57:46 pm

I'm sure there is a ton of EX footage out there that demonstrates progressive panning. One example I know of is my own, where I do a 180 degree pan in about 2 seconds with the camera recording HQ 35 VBR 1080p 30. If you're interested it's at my website and the panning shot is about 5 seconds into the movie (so you don't have to watch the whole thing). The movie has been down converted to a 600 x 338 frame size.

http://www.reeltimevideoworks.com/wedding_samples.php

Click on the movie called:

95Crave FM Contest
sample3

- Don




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Chris Babbitt
Re: More Help please on Bad strobing on YPbPr output
on Jul 24, 2008 at 9:41:43 pm

Don,
Yes, that is similar to what I am seeing in the viewfinder, but when I playback, the effect on the monitor is about 4x worse. Incidently, I thought you were a nice guy before, but you've gotten even nicer since becoming a forum host. Please, don't lose that, even after having to deal with all the stupid posts....like mine.



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Steve Wargo
Re: More Help please on Bad strobing on YPbPr output
on Jul 25, 2008 at 5:40:44 am

[Chris Babbitt] "I thought you were a nice guy before, but you've gotten even nicer since becoming a forum host. Please, don't lose that, even after having to deal with all the stupid posts....like mine."

Now isn't that special?


Steve Wargo
Tempe, Arizona
It's a dry heat!

Sony HDCAM F-900 & HDW-2000/1 deck
5 Final Cut (not quite PRO) systems
Sony HVR-M25 HDV deck
2-Sony EX-1 HD .


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Don Greening
Re: More Help please on Bad strobing on YPbPr output
on Jul 25, 2008 at 7:27:46 pm

[Steve Wargo] "Now isn't that special?"

Indeed. Comments like that usually elicit my "Aw shucks, it ain't nuthin' " response.

Thanks, Chris.

- Don



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Ron Shook
Re: Bad strobing on YPbPr output
on Jul 28, 2008 at 4:26:33 pm

Chris,

[Chris Babbitt] "However, when I connected the camera to my HD monitor (both a 32" LCD and a 56" DLP) using the component cable, the pans look so bad, it's as though something is really wrong. I noticed that the YPbPr output on the camera is limited to 60p even though the footage was shot in 24 or 30p (page 117 of the manual)."

Just speculating from what you've said, but I suspect a technical issue revolving around pull-up or pull-down (I can never keep them straight.) Whether it's correctable by some camera (or monitor) setting, I don't know, but as others have said, if you take your footage properly through your NLE and output to a standard viewable file, I think that you'll find the problem will disappear because the proper image cadance processing will be applied.

Ron Shook



Ron Shook
Shoulder-High Eye Productions
CreativeCOW Forum Host for Discreet edit*


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