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Old March 8th, 2009, 01:22 PM   #1
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Rolling Shutter and flash (again, sorry!)

I know this issue has been beat to death here, but to be frank I'm a little lazy this morning to search through all the threads to find some possible answers here.
The rolling shutter debate never really caught my attention before, as I have not (until now) really seen it manifest itself..... but last night at a paparazzifest I got a very clear example of exactly what the rolling shutter issue is about.
I had to be shooting 108060i per the client's requirement. Would a progressive mode have mitigated this somewhat? I have heard that some of the 'half' frames can be removed in post to improve the clip? I want to be able to provide the client with some direction on how to deal with this..... any suggestions would be welcome, as well as ways to minimize this (if possible) in the future.
Sorry about the subject in the clip. I know it's a weekend, and it's early. Hopefully, you've all had breakfast already...
cheers
Derek
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File Type: mov RollingShutter.mov (769.6 KB, 815 views)
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Old March 8th, 2009, 01:49 PM   #2
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I've never dealt with this myself, but I seem to remember reading that people would edit in one frame of full-screen white to cover over the 1/2 screen flash. (hopefully you don't have too many of them that need to be covered)
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Old March 8th, 2009, 01:51 PM   #3
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Never mind. I should have looked at your footage before I posted. I have no idea how to "fix" that mess. Sorry.
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Old March 8th, 2009, 02:04 PM   #4
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I think I would plead ignorance of any fault. If you shot on any CMOS camera you would have a similar outcome. As for fixing I suppose supering a white patch is possible.
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Old March 8th, 2009, 02:24 PM   #5
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I shot a wedding with two or three photographers on either side of me using their flash and man the EX1 cannot handle this but not one person that has viewed the footage said anything about the rolling shutter. I look at the footage and cry but Iím looking for this effect and to the untrained eye they just donít see it as a problem other than a camera flash from the photographer. This rolling shutter effect happens in both p & i shooting.
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Old March 8th, 2009, 02:53 PM   #6
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Did the client complain?

If not, I wouldn't worry about it. And don't ever mention it or they'll look for the problem.

It's much more important to get "the shot". And all those flashes firing off is tremendously more distracting than the partial-frame problem.

If the client complains then you have no choice but to use a different camera.
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Old March 8th, 2009, 03:34 PM   #7
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It's interesting how something "new" is generally viewed as bad rather than different.

These days it seems almost all 1 chip consumer cameras are CMOS. The results are that many people are used to the look and don't think of it as anything other than unavoidable normal.

Others, professionals (and their clients) or people who've used CCD cameras are obviously more sensitive to it.

Flashes themselves are annoying certainly the barrage you see in your video would look ugly either way. It's a matter of which ugly you prefer.

I do see some hard horizontal and vertical lines in flashes that I've never seen other examples of.

JVC does make 1/4" and 1/3" CCD XDCAM EX codec cameras now. The tradeoff is the smaller chips so I suspect the low light performance may not be as good. The alternative if you want 1/2" CCD is the F335 XDCAM HD camera.

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That rolling shutter flash issue is related to how the CMOS chip is being scanned (both rate and method). I wonder if dropping the shutter to 1/30 when shooting at 30fps would cause just enough smear to alleviate the issue. Basically smearing the flash. The more something moves the more it smears so relatively motionless talent would reaming reasonably sharp. This may not work. I've never tried it. I wonder if anyone has experimented with this.
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Old March 8th, 2009, 03:38 PM   #8
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We are more worried about the problem than the client would ever be. In fact I put money on it they would never notice.

However, I use a plugin and just turn any damaged frames into a flash. Problem solved.
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Old March 8th, 2009, 03:44 PM   #9
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Steve the clients will certainly notice if you slo-mo the footage. There's a good discussion going on here:
http://www.dvinfo.net/conf/sony-hvr-...ml#post1024375
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Old March 8th, 2009, 03:49 PM   #10
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I thought I'd upload the images of the kinds of frames/flashes I saw in your video.
Theres:
Normal
Flash which looks like a normal full flash frame
Bottom Flash which was followed by top flash which is typical in rolling shutter. This is why I'm wondering if dropping the shutter speed might smear them.
Horizontal line flashes of varying brightness/darkness. I haven't seen that before and I suspect that's a result of multiple cameras flashing. It these horizontal banding flashes which look the worst in my opinion.
Attached Thumbnails
Rolling Shutter and flash (again, sorry!)-normal.jpg   Rolling Shutter and flash (again, sorry!)-flash.jpg  

Rolling Shutter and flash (again, sorry!)-bottomflash.jpg   Rolling Shutter and flash (again, sorry!)-topflash.jpg  

Rolling Shutter and flash (again, sorry!)-horizflash.jpg   Rolling Shutter and flash (again, sorry!)-horizflash2.jpg  

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Old March 8th, 2009, 04:00 PM   #11
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Dropping the shutter speed is good. I've just done some tests this afternoon with the EX1 on its slowest shutter speed, and electronic flash lights the whole frame as far as I can see - none of these nasty 'partially exposed' frames were evident.
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Old March 8th, 2009, 06:04 PM   #12
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all this talk of flashes and rolling shutters and all I see is Paris's lazy eye... LOL
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Old March 8th, 2009, 08:12 PM   #13
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Looking at the clip I think the effect looks a bit weird but nowhere (in that clip) did you get completely washed out and there are enough good frames for the eye to integrate -- I suspect viewers will accept that is the normal consequences of flashes being fired. It might be successfully processed in post (working on individual frames) to shade over-exposed portions, but I doubt this would remove it entirely and may make it visually worse.
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Old March 8th, 2009, 08:38 PM   #14
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Quote:
Originally Posted by Erik Phairas View Post
all this talk of flashes and rolling shutters and all I see is Paris's lazy eye... LOL
I agree, when I see that long neck in creamy skin, rolling shutters seem a long way from my mind.
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Old March 8th, 2009, 10:13 PM   #15
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To me, this is a situation where the rolling shutter effect does not matter.

As stated, the amount of flashes going off would ruin any footage.

I would be sensitive to the rolling shutter effects when just a few flashes go off and the horizontal lines are more visible. Then it looks like a playback or capture error to me.
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