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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 April 24th, 2007, 03:19 AM   #31
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Originally Posted by Steve Mullen View Post
The V1 does not behave like the HC1 or A1. So bringing the HC1 into this thread offers nothing.

24 isn't shot like that either. Every shot is VERY controlled by pros who know how to shoot quick moves at 24fps and have it look great. (Moreover, the HC1 doesn't shoot 24p if that was the frame-rate it was shot at.)
I brought the hc1 to the mix because I heard complaint in a different forum about the V1's rolling shutter effect by someone. Bringing the hc1 to the mix will give me a clear idea of is the v1 the same or different depending on what people say. That clip also clearly shows the effect at its maximum. I didn't specifically look for it when I was shooting, but when I went through the material I saw a lot of...interesting motions :)

I shot with the dvx100 and hc1 at the same time the other day and the dvx100 did indeed look somewhat "more right" in motion shots even with a 1/50 shutter.

The problem also appears when doing telephoto shots and something passes along the frame. Like shooting from a moving car into the horizon. When something passes in front it will look like shit and there's nothing to do about it. Also the effect will be more apparent in a 25p clip than a interlaced 50i clip because one frame is longer in view.

I used a pal hc1 so a 25p clip was very easy to get. And I don't really see the point in belittling this. The effect maybe nothing to you, but I'm interested in seeing clips like this for the v1. I read a brochure once where Sony said the readout speed was 4x for the V1, but I don't know how it translates to real life. The hc1 (and hc3/hc5/hv10 atleast) seems to have the same 1/60 speed for the rolling shutter to go from the upper part of the frame to the lower. One of the reasons these cameras use a 1920x1440 sensor is to minimize the apparentness of the rolling shutter by cropping the lower and upper part of the frame. The v1 doesn't do this so I'd assume it is indeed faster.
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Old April 24th, 2007, 03:36 AM   #32
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Originally Posted by Douglas Spotted Eagle View Post
The issue seems bigger than it is due to one person advocating that it's a huge problem and another advocating that it's not any kind of a consideration at all. IMO, neither is correct.
That's true. Reading all of the posts I'd say I'm in the minority here because of my shooting style (high shutter, lots of kungfu, slowmotions, tracking shots).
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Old April 24th, 2007, 04:54 AM   #33
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I was really confused by HC1 footage being used in a V1 rolling shutter discussion. I've never seen anything like that at all with the V1, but I'm not doing that sort of stuff so I thought I might have missed something.

In looking at Spot's footage, I can now see the rolling shutter artifact that looks like strobing. I examined the footage and it looks like a VERY fast shutter. Even with dramatic movement, there is no motion blur. I believe I've stated in the past that I think the V1 is probably just fine up to 1/250 and don't have a reason to ever go faster. I am curious as to the shutter speed used in the sit_flutter.mov clip. I don't think I will ever shoot with such dramatic movement and a really fast shutter, but it would be nice to know the limit where artifacts start to happen.
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Old April 24th, 2007, 05:12 AM   #34
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A possible solution!

I think I just had a "Eureka" moment. I noticed in sit_flutter.mov that a lot of the shutter-induced strobing artifact was in a section of footage with less motion than a section with significant camera movement. When the camera flips over, there is just a bit of this artifact and that is when I would expect the greatest problem.

Why would there be more artifact when the camera operator is flying level?

I think I know a possible answer: Steadyshot.

During gross movement of the camera, the image stabilization will be pegged at maximum/overwhelmed so it won't be moving during the exposure. On the other hand, small but fast vibrations may be causing the optical stabilizer to move during the actual exposure. I would guess that maybe buffeting airflow could be inducing the problem.

I wasn't there, but I'd like to know if Steadyshot was turned on. Since there are frames with incredibly fast motion without obvious artifacts, I bet only the super-fast reactions of the stabilizer are able to cause this problem.

If this is the case, problem solved. Stabilization can done in post, so people doing extreme shots with a fast shutter can plan for this and practically eliminate the artifacts.

I get big nerd cred if I'm right and someone then owes me a Kuaaina burger!
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Old April 24th, 2007, 06:48 AM   #35
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Originally Posted by Marcus Marchesseault View Post
I get big nerd cred if I'm right and someone then owes me a Kuaaina burger!
You're right. The hc1 has somewhat the same effect when the stabiliser corrects movement. It doesn't stop the rolling shutter though, so the stabilised footage will be "stable" but it will wobble. And you can't eliminate it in post. The wobbling will stay. The alternating brightness will go away though.

I just watched the clip and there is some small wobbling when going frame by frame, there aren't that many straight lines though to evaluate. I'm actually thinking that maybe the V1 isn't faster at all, but nobody else notices or cares about the phenomenon except me :)

Oh well, enjoy your cameras, I can live with the rolling shutter although it sometimes forces me to limit my shutter and movements.
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Old April 24th, 2007, 08:45 AM   #36
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Let me ask for some clarification here...

In the sit_flutter clip, I see two different types of artifact. I see the horizontal dark strobing bands in the last part of the clip. I also see the horizon "bend" as the camera pans. It looks a bit like the distortion you would get with a fisheye lens.

I was under the impression that it's the latter artifact that is caused by the rolling shutter. Am I wrong?
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Old April 24th, 2007, 09:06 AM   #37
 
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Doug, the extreme wide angle is just that, an extreme wide angle on the lens. It's only the strobing that you should be concerned with, we generally use extreme wides in most aerial work when shooting for fun vs commercial use.
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Old April 24th, 2007, 02:03 PM   #38
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Thanks, Spot.

At the risk of going OT, why do you use a WA on a jump cam? Is it because a lot of your shots are done while physically very close to the subject? Holding hands, other relative work?
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Old April 24th, 2007, 06:26 PM   #39
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I'm still very interested in knowing the shutter speed used in the aerial footage and whether or not image stabilization was engaged. Turning off image stabilization to reduce strobing could be an important step for V1 users that use high shutter speeds.

In the clips provided, the "wobbling" on the V1 looks dramatically lesser than that on the HC1. I really didn't notice it on the V1 footage until I focused on finding it. The HC1, on the other hand, showed obvious and extreme diagonal distortion.
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Old April 24th, 2007, 11:12 PM   #40
 
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Footage is at 1/120th, but frankly, I could have avoided the issue had I managed the angle better. I usually do. It's a combination of things, and this clip is rare.
However, I do shoot often at 1/120, because I'm often slowing my footage down, and need the additional speed to get a good slo-mo image.

Wides are used for multiple reasons, but the most important is that we're interested (usually) in showing the breadth of the sky while pulling the subject to the fore. After all, it *is* the biggest playground in the universe for the child-like fun we have up there. :-)
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Old April 25th, 2007, 02:42 AM   #41
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How about image stabilization?
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Old April 25th, 2007, 08:57 AM   #42
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For anyone who thinks a rolling shutter is a non issue a quick trip over to the Reduser forum might convince you otherwise. Just because the eye doesn't see things doesn't mean it isn't an issue for compositing.
As for using faster shutter speeds, there's many good reasons, slomo is one, image stabilisation in post is another.
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