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Sony HVR-V1 / HDR-FX7
Pro and consumer versions of this Sony 3-CMOS HDV camcorder.


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Old October 9th, 2007, 04:30 PM   #1
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Frame-split camera flash? Help?

I am shooting 1080p with my V1u onto sony blue tapes. I don't know if this is a tape problem or a general HDV problem, so please help me out.

Below are three frames from some skating footage I was shooting. Can anyone tell me what is going wrong? I am not using HDV tapes, but i've heard that the sony blues work just as well.
Thanks,
-Jeff

http://i24.photobucket.com/albums/c4.../hd_fu_fr3.jpg

http://i24.photobucket.com/albums/c4.../hd_fu_fr2.jpg

http://i24.photobucket.com/albums/c4.../hd_fu_fr1.jpg

Last edited by Jeff Kolada; October 9th, 2007 at 04:31 PM. Reason: fix picture links
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Old October 9th, 2007, 05:14 PM   #2
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Is this during a photo flash? If so, it's a know issue with HDV. The flash screws up the compression/GOP resulting in images similar to those posted.
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Old October 9th, 2007, 06:46 PM   #3
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I have had flash on HDV at music gigs which looked "normal" but I was using the slow shutter speed of 1/50 sec. I do not observe much motion blur in the grabs which suggests to me a higher shutter speed of say 1/250th or higher may have been in use. Only guessing though so don't pay too much heed to my comment. There is an interesting artifact around the top of that tripod or light stand. Was that a flash source? If there was no flash, was your camera anywhere near an operating mobile telephone (cellphone)?

Last edited by Bob Hart; October 9th, 2007 at 06:54 PM. Reason: added text.
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Old October 9th, 2007, 07:38 PM   #4
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This is exactly the "rolling shutter" effect you get with photgrapher's flashes and/or very fast movement.

To do with CMOS chips reading its info from top to bottom and you wont get it with CCD's.

Nothing to do with your tapes.

Check it out yourself by setting the camera up in a low light situation then get out your still camera and pretend your a photgrapher. Then view the tape back frame by frame over the flashes! (Worse in slow motion).

The main reason I bought an FX 1 for weddings and leave my FX 7 in the car as back up.

Cheers Vaughan
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Old October 9th, 2007, 07:49 PM   #5
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Have notice on V1E as well. So any tips or setting up shutter speed of 1/100 sec above?
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Old October 10th, 2007, 02:17 PM   #6
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Have notice on V1E as well. So any tips or setting up shutter speed of 1/100 sec above?
Nothing you can do about it, basically. It's a design prob with how Sony does CMOS. Try shooting lightning and you'll see it as well.
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Old October 10th, 2007, 03:40 PM   #7
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IMO shutter speed won't really resolve the "problem" - it's strictly a matter of how the imaging chip is "read", which is not all at once - you'll notice from the pictures posted that flashes result in horizontal "bands", some of which show the exact moment of the flash, while adjacent bands show the moment before or after - we're talking milliseconds here - extremely small slices of time. I've had shots while experimenting where the chip captured the whole frame "lit", others show the banding... it's a function of the synchronization with the event...

At some point, CMOS will probably be capable of processing complete "frames" in one "chunk", but for now it seems that for all the CMOS advantages, this is the one fly in the ointment... and all CMOS based cams, not just Sony, exhibit the same behavior.

I've managed to work around it, and even with the flaws, it's better than how some individual frames looked when a flash went off with my SD cams...
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Old October 10th, 2007, 07:09 PM   #8
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Nothing you can do about it, basically. It's a design prob with how Sony does CMOS. Try shooting lightning and you'll see it as well.
Thanks. coming projects will see how was it on more lights
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Old October 10th, 2007, 07:21 PM   #9
 
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Nothing you can do about it, basically. It's a design prob with how Sony does CMOS. Try shooting lightning and you'll see it as well.
It's how low cost/small CMOS functions. Not a Sony, Canon, JVC, Panasonic, or anyone else does CMOS.
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Old October 11th, 2007, 01:13 AM   #10
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Originally Posted by Dave Blackhurst View Post
At some point, CMOS will probably be capable of processing complete "frames" in one "chunk", but for now it seems that for all the CMOS advantages, this is the one fly in the ointment... and all CMOS based cams, not just Sony, exhibit the same behavior.
Be careful when you say "all CMOS based cams." I agree that the low cost ones do but not all. Some of the higher end CMOS cams employ a global shutter system instead of a rolling one.
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Old October 11th, 2007, 08:07 AM   #11
 
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Exactly. RED, as one example, uses a CMOS sensor as well.
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Old October 11th, 2007, 08:27 AM   #12
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I shoot a lot of weddings. When I first used my V1 and saw all the rolling shutter effects from photog flash I thought the footage was going to be crap/useless.

The first time I delivered a wedding I cut as many flashes out as possible and hoped they would not notice/complain. As it turned out they not only did not see the rolling shutter but loved the look of the V1 footage.

Now I do not worry about the flash it is part of the event I have never had any client say anything about the effect. I was all prepared to explain the new technology, CMOS, rolling shutter, photog flash, and no one ever asked. So I just let it go.

If it really bothers you, you could enhance the flash and white out that frame. Or darken or lighten the half that is effected to make it not so noticeable. But for events I just donít see the need.
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Old October 11th, 2007, 10:56 AM   #13
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The rolling shutter flash effect is a problem, but I've found that most consumers don't even know it's there. It's acceptable for flash photography, but I'd guess it pretty much f's up a lightning shot.
I've seen it all over the news recently. I think it was on some footage of Britney Spears with the Paparazzi clicking happily away and this footage was on CNN, FOX News, ABC, NBC, all the major networks. They didn't seem to have a problem using it. That's not saying much though as they routinely use video footage shot with cell phones.
It's not just a Sony problem as someone said before. Even the Red One suffers from the dreaded CMOS rolling shutter problem... and sheer... CMOS technology isn't all grown up quite yet.

*EDIT*
It helps to read the entire thread. It would appear that several people have already pointed out that RED uses a rolling shutter too. Oops.
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Old October 11th, 2007, 11:17 AM   #14
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Fopp !! The sound of my foot coming out of mouth. I misread the title of this thread FX1 for FX7 so my comment above has absolutely no relevance whatever. Sorry about the misinfo.
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Old October 11th, 2007, 01:35 PM   #15
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thanks alot all. Looks like I'm gonna have to play around with it a little bit and see if i can do anything to reduce it, or just cut some footage. As a first post in this forum, I am really liking the kind of feedback I am getting. Thanks to everyone who commented.
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