Motion Problems using JVC GY 100

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PandoraFilmmaker

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I've been shooting with the JVC in 720P 30p mode. Recently I've tried some car window and wheelchair dolly shots and the results were horrible. With the car shots, I thought the issue might be focus. With the dolly shot, the situation was more controlled. I was dollying past a group of people walking towards the camera down a hallway. I tried it several times, focus at 10 feet, focus at 5 feet. The F stop ranged between 2.8 and 4. Shutter speed 60.

The problem is that nothing ever looks quite in focus. When I applied slow motion in FCP, the shot has a jittery look, most frames blurred. Ironically I got better results with motion using my old Sony TRV 900. What do you think is the problem? Does this require a higher shutter speed? Any thoughts appreciated!

Also, I had the motion smooth feature on, but the shot still had a jittery look.
 
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You're shooting at 30fps, not 60fps (as in TRV900). You can't compare an interlaced image shot at 60fps to a progressive image at 30fps. The progressive picture is 1/2 the frame rate. You may want to try the 480p60 mode instead in order to get your slow motion sequence. Also if you don't want blur, you need to increase your shutter speed to get stop motion from frame to frame.

I've made a demonstration video over on dvinfo.net which displays how to get 480p60 silky slow mostion and how to uprez as well.

have fun...
 
I've made a demonstration video over on dvinfo.net which displays how to get 480p60 silky slow mostion and how to uprez as well.



Can you give me the link to this article. Couldn't find it.

Also, why couldn't I shoot in 720p 60 ... or is it not supported by FCP?
 
The probelem is that the JVC GY-HD100 does not record in 720p60. You have to get the Gy-HD200 for that capability. However the HD100 does output 720p60 through the analog component outputs but you have to buy your own recording equipment in order to capture this framerate.
 
Androbot is right. You can't get 720p60 to the tape on an HD100 but you can get 480p60 to tape and uprezz with really good results.

Click here for dvinfo.net Post. This post is part of a 4 part series I did on HD-100 material. It should give you ideas for your NLE.

good times....
 
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Thank you. So my next question is, why doesn't the strobbing effect occur on film at 24 fps? Is this - usually undesired effect - unique to video in progressive frame mode? I've certainly never seen it happen on panning, tracking shots in film.
 
Look harder; film suffers the exact same motion strobing. Watch the opening segment of "Sahara", or the POV shot of Johnny Depp in "Pirates of the Caribbean" when he's first sailing to the dock on the sinking ship, or almost any sideways-scrolling shot in "Network". Film strobes exactly the same way 24P video does. It's just that film shooters have been working with it for over 100 years now and have developed adept techniques to deal with it.
 
Barry's right, it's all over film. Take a look at the Andy Griffith Show on TV. You'll see the same stutter if you watch the background and not the actors. Usually the camera follows the talent and therefor the effective pan rate is reduced or almost no pan (because the camera follows the actor with framing). You'll have to look at backgrounds to see the same stutter in almost everything that is filmed.
 
Exactly -- film shooters are adept at keeping a subject occupying the viewer's attention, so that the viewer doesn't notice how badly the background is strobing.
 
So it's all about distraction eh - like in a magic show? Despite what you say, I've never noticed it on films - but I"ll take a look! I wonder if there's a different , more noticebale quality to video strobing. I'm seeing it all the time now on other 24p video-- but maybe it's because I'm looking for it.
 
Start looking for it in film and you'll see it everywhere.

The deep depth of field of video may make it a bit more noticeable in that the background might be more blurred in most 35mm film shots, but with identical depth of field the strobing is absolutely identical between film & video; I've tested it by setting a 16mm camera and a DVX side-by-side, both on wide angle with infinite DOF, shooting the exact same subjects at the exact same times, then split-screening the results. The motion handling and strobing are ABSOLUTELY IDENTICAL.
 
Barry_Green said:
Start looking for it in film and you'll see it everywhere.

The deep depth of field of video may make it a bit more noticeable in that the background might be more blurred in most 35mm film shots, but with identical depth of field the strobing is absolutely identical between film & video; I've tested it by setting a 16mm camera and a DVX side-by-side, both on wide angle with infinite DOF, shooting the exact same subjects at the exact same times, then split-screening the results. The motion handling and strobing are ABSOLUTELY IDENTICAL.
Click to expand...

YEP.. I second that. Was watching TCM's Rita Haworth films (watching on a standard interlaced TV) from the 40's and opening titles (billboards along the side of the road) took 7 seconds to travel from right to left and that was about as much as one could stand. I must say most people don't notice it. I had to record a softball game last week. My sony DV is still in the shop for 8 weeks now, so I used my JVC HD10 that I've been experimenting with. I won't go into it's shortcomings here.. but shot 720p 30fps.. kept my pans and zooms to either slow or very fast.. slapped up on thier 42" pioneer plasma... and no one noticed any strobing.. I saw it, but it wasn't bad.. Then I downconverted to SD DVD anamorphic widescreen, and they and everyone says it looked better than my Sony TRV900 ever did. AND IT SHOULDN'T! 3 chip vs 1 chip, 60 interlaced vs 30p. Everyone SHOULD like the sony better, but everyone liked the downconverted HDV instead. If I had paned at a medium speed, they might not have felt that way. Personally the only camera I think most of us would be happy with would be a Varicam. But I can't afford one...
 
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