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Old June 25th, 2009, 07:55 PM   #1
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Join Date: Feb 2007
Location: Apple Valley CA
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Is 30P really enough?

I was playing a bit with the Sony HX1 (yeah, I know, a toy, but kinda cool). It of course has a 30P video mode.

Shot some pictures and video with an XR500 and the HX1. Each camera of course did noticeably better in it's primary discipline, but passably in its secondary mode, not great, but passable and usable in a pinch or if you don't get too picky.

Playing back the clips with Sony's included PMB app, the one thing that really stood out to me was the "strobing" of the 30P video when there was motion (kids swim class in a pool - LOTS of motion). The 60i from the XR looked excellent, but even though the 30p looked OK, there was a noticeble stuttering/strobing that to me detracted from the overall quality of the image. I noticed the baseball clip someone else just posted exhibited the same sort of thing.

I've shot a couple things with the HX1 where the motion wasn't quite as drastic, and didn't notice anything, but I'm wondering if the 24/30P acquisition mode (on any of these cameras really) is adequate for those "high motion" type shoots?

I like the "fusion" camera concept, but am beginning to wonder...
Dave Blackhurst is offline   Reply With Quote
Old June 27th, 2009, 11:34 AM   #2
Join Date: Nov 2006
Location: San Angelo Texas
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I looked at those baseball clips and couldn't see any "strobing".

I used 30p on a project with living history cavalry drills and on the cavalry charges I though it handled motion fairly well. I had to pan with the "charge" and the motion blur in the background was just right with most of the horse and trooper sharp enough. Horse's legs and in some case trooper's leg were "motion blurred" but the effect was just right and like I've seen in many theatres.

The camera was a Canon HF100.
Bruce Foreman is offline   Reply With Quote
Old June 28th, 2009, 03:50 AM   #3
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Location: Eugene, Oregon
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Strobing or Fluttering Mostly a Playback Problem

I've found that much or sometimes all of the fluttering that is seen in video from the HX1 or other progressive-shooting CMOS cameras, is due to computers or playing programs not being adequate or not specifically tuned to the format or bit-rates. When I play footage that I shot with an HX1 and also from an SX1, using a quad-core computer and Splash Beta 3, almost all of the irregular motion I see with other players, is not visible.

Regarding action video of things like horses' legs or birds' wings, strobing may be due to having too fast a shutter speed. With an interlaced camcorder that can have its shutter speed manually changed, by setting it at 1/60th-sec., the legs or wings are nicely blurred, as they would be if you saw them directly. With a shutter speed of 1/100th-sec. or higher, sharper images of the fast-moving parts will make them appear to be in several positions at once, which spoils the look of the video. Perhaps a 30p camera would need to have a shutter speed of 1/30th-sec., to achieve the right effect, but I've never used one that could have its shutter speed adjusted.

Another thing about the HX1, is that the 720p video looks sharper than the 1080p mode. Steve Mullen suggests that this might be caused by the anti-aliasing filter being optimised for the 720p video and not so well for the 1080p. In any case, I got much better video from the 7 Mbps 720p mode, than from the 12 Mbps 1080p, with my HX1. Its video was amazingly good in dim light, while that of the SX1 was not so good and very noisy when the light was low.

This video was shot about 15 min. before sunset, in a deeply-shaded streambed, with an HX1:
This one was shot about 10 min. before sunset, nearby:

These were both at full zoom, with 640mm. If you have a free Vimeo subscription, you can download the full video files, for much better playback quality.
J. Stephen McDonald is offline   Reply

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