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JVC GR-HD1U / JY-HD10U
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Old July 9th, 2003, 06:34 PM   #16
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I took another look at the footage with my friends walking around. Not too bad, but I need to do more tests.

heath
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Old July 9th, 2003, 09:30 PM   #17
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<<<-- Originally posted by David Newman : Steve, there is not "real" double image just as there is no spoon. :) It is in your head (and others.) Yes 30p is slower than what the human eye expects for smooth motion. 24p is 20% worse than 30p, so it suffers from motion aliasing (more accurate term than strobing or double image). The reason you often don't notice this in film (24p) is that the shots are taken with this knownledge in mind. -->>>

This is what I wrote to JVC for their comment:

"Because our visual system integrates images together into one if they appear within a space of about 1/30th second (which is why interlace works) then -- displaying at 60fps -- we will SEE 2 images when objects are being displaced spatially because they are moving."

Seems like we are saying the same thing.

But, here's what bothers me. You say we can see this with film if motion isn't dealt with. I've watched a lot film -- and shot film too without worrying about motion. (Think of NFL highlights as material that violates shooting rules!) I've never seen what I see with the HD10.

Another issue. Shooting at 1/30th S which is the JVC recommendation for reducing the problem-- is equivilent to shooting film with a 360 degree shutter which can't be done.

I also know several cinematographers who dispute the common asseration that the "strobe look" of low frame-rate video looks like the motion aliasing of film.

And that's my concern. While I do think it is in our eyes, my eyes don't see what I see in Frame-mode or 710p30 -- on a movie screen.
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Old July 9th, 2003, 10:13 PM   #18
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Steve,
Given that we can prove there is nothing wrong within each frame, and film is effectively doing the same thing at a slower frame rate (180 degree shutter or the magical JVC 360 degree -- you choose .) The only place to be pointing fingers at is the human visual system. If you shot the same scene at 30p with film and with the HD10, the motion aliasing would be identical. Note: 30p film is not unheard of as the NBC show "Friends" is shot at 30p rather than 24p or 60i. This is not to say there aren't huge other differences, 30p is just not one of them.

One possibility is as the gamma curves of the JVC camera matches that of video, so your brian is trained to expecting video frame rates. Like DV projects transfer to 35mm -- the motion is all wrong (but for other reasons.) Whereas slower film sources we forgive its motion aliasing, as the lighting/gamma is sooo much better. Just an idea.

Anyway I think the 30p is beautiful, and it can produce stunning outputs. I have been shooting 30p since 1997.
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Old July 9th, 2003, 11:16 PM   #19
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<<<-- Originally posted by David Newman : Steve,
One possibility is as the gamma curves of the JVC camera matches that of video, so your brian is trained to expecting video frame rates. -->>>

You may have it. It looks like VIDEO not FILM -- so my brain is processing it like it does interlace video.

Today i shot both 1/30th and 1/60th observing the rules of film. Now either my brain is getting used to it -- :) -- or the film rules work! I panned with walkers and as the theory says -- the eye can't see what's happening in the background.

I'm now comfortable that anyone who complains about "strobing" can be helped by shooting differently.

I've been watching on an 8 foot screen, where I also watched 24p from the DVX100. The 24p did look like 16mm film. It amazed me!

This definitely does NOT look like film. It looks like the Grammies shot live on HD. Since I've watched HD for over a decade -- I used to live in Japan -- my brain sees it as HD video. It should be 60 images per second. It's not. But it's not film either.

Thank you for joining in!
Steve
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Old July 9th, 2003, 11:28 PM   #20
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<<<-- Originally posted by Steve Mullen :
I've been watching on an 8 foot screen, where I also watched 24p from the DVX100. The 24p did look like 16mm film. It amazed me!

This definitely does NOT look like film. It looks like the Grammies shot live on HD. Since I've watched HD for over a decade -- I used to live in Japan -- my brain sees it as HD video. It should be 60 images per second. It's not. But it's not film either.

Thank you for joining in!
Steve -->>>

I can live with Grammies on HD.

heath

ps-any idea why dumping to tape from FCP to the HD10 (DV) I'm getting sparkles/hits on the image? I posted elsewhere...
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Old July 10th, 2003, 03:11 AM   #21
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I just posted some info on the "double image" effect in this thread:

http://www.dvinfo.net/conf/showthread.php?s=&threadid=11779&perpage=15&pagenumber=2

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