How to get rid of Motion blur on fast moving object?

Brian Drysdale · March 25th, 2007, 09:49 AM

Quote:

Originally Posted by Gonzague Alexandre

Ok but....

on a HVX we have different shutter speed like 500, 1000 or 2000... but when you are in 30 or 60... I cannot use those higher setting ?!?!? I am confuse

Lets see if I have a 500 shutter speed in order to respect a full digit rule (no number like 1.33) I must have a 25fps, 1000 a 50... How can I do that.... I am really lost here

You can use the higher shutter speeds if you want a "Saving Private Ryan" effect. They can work with water spray when you want a sharp strobe type effects on the water droplets. However, if shooting you're at 24p, 30p or 60p the high shutter speeds should be regarded as an effect.

The standard shutter speeds are 1/48, 1/60 and 1/120 respectively, if you go higher than these you need to aware that you are increasing the jerkiness of the action.

A car moving through a static shot doesn't need a high shutter speed. You're not trying to freeze action as stills photographer does, the motion blur smooths the action.

If shooting progressive, make sure the shutter is switched on.

R Geoff Baker · March 25th, 2007, 09:54 AM

'Cannot' ...

You can always use high shutter speeds when the subject is motionless. And in general, if the object is moving towards or away from you, you can use much higher speeds than if the subject is moving laterally. And if the object is distant, you can use a higher speed than if it is close ...

As for the full digit rule ... I don't know where you are going with that. In general, shutter speeds are in full stop increments -- each notch halves the speed, and so drops the exposure by one full stop. But there is no rule in that -- if the speed dropped by less than half, the aperture would open a little to keep exposure accurate. 30/60/125/250/500/1000 is not essentially any different than 25/50/125/250/500/1000 ... the percentage 'jump' from 50 to 125 is mildly significant, but once done the rest of the values hold.

HTH

GB

Brian Drysdale · March 25th, 2007, 11:06 AM

You're better using neutral density filters for controlling exposure rather than shutter speeds.

Gonzague Alexandre · March 25th, 2007, 05:11 PM

Thanks Guy... I need to play more and to more test until I reach the perfect setting... unfortunately time is always my enemy...

Once again Thank you for your kind help

Sergio Perez · March 26th, 2007, 01:53 AM

If sound is not important, I would suggest shooting 30pn with 60p slowmotion. Than speed up in post (double speed). Shutter at either 125 or 250. Try this out.

As for native 30pn, if you don't want the moving car to stutter, try Panning with the car CENTERED. The scenery will blur, but the car will stay sharp. Shutter speed of 125 should be the further you go.

And do turn OFF OIS, like the fellow DVInfo member pointed out. OIS adds a layer of blur, EDIT much noticeable in FILM LIKE Progressive frame rates- 30p, 25p or 24p . It was designed to work in Interlaced modes, EDIT or smooth progressive frames like 50p or 60p, not in film like frame rate modes.

R Geoff Baker · March 26th, 2007, 04:28 AM

Why would an 'Optical Image Stabilizing' system care if you were shooting interlace or not? What 'layer of blur' could the moving lens of the OIS system introduce?

Turning off OIS to smooth panning makes sense, if the OIS is sensitive to the rate of pan ... but frankly, rest sounds like nonsense ...

GB

Sergio Perez · March 26th, 2007, 04:45 AM

Quote:

Originally Posted by R Geoff Baker

Why would an 'Optical Image Stabilizing' system care if you were shooting interlace or not? What 'layer of blur' could the moving lens of the OIS system introduce?

Turning off OIS to smooth panning makes sense, if the OIS is sensitive to the rate of pan ... but frankly, rest sounds like nonsense ...

GB

Well, what I meant was that OIS affects image movement you're recording in a progressive mode that's bellow 60p or 50p. OIS compensation for movement seems to add a layer of compensation thats visible in these frame rates. In interlaced 60 i and 50 i footage, this is also a non-issue, due to the natural smoothness of the image. It can add a small layer of softness in pans, but not much noticeable.

That's what I meant. 60p/50p frame rates also work fine with OIS. Its just when you're working with film frame rates that OIS looks particularly bad. Saying only interlaced was my mistake. I wanted to say OIS works particularly bad in FILM LIKE frame rates, slower than 60p or 50p-make it 30p, 24p or 25p.

Nonsense?

R Geoff Baker · March 26th, 2007, 05:21 AM

Maybe nonsense is harsh -- I surely didn't mean to stifle discussion.

But I fail to see how an optical lens, tilting in response to axis movement of the device ... can add a layer of anything. The lens tilts in and the image is respositioned on the sensors. The sensors, and the encoder, are 'dumb' to the action of the lens -- the reason to turn the system off during a pan is mechanical ... the tilt defeats the movement of the pan momentarily, then gives up and the image jumps to the new position, then the system tries to defeat the pan, et cetera. It is only because the OIS doesn't 'know' that you intend to move the image that it fights you.

But try as I might, I can't make sense of the rest of your description of the operation of the optical image stabilizing system. It is blind to frame rates, it doesn't add layers of anything, it is a 'simple' optical mechanical device, rather like a tripod's fluid pan head ... and simply can't be responsible for the effects I understand you to be describing.

GB

Sergio Perez · March 27th, 2007, 08:17 PM

Mr Baker:

Your description of the OIS system is correct, but what I mean by the "Layer of compensation" is what you describe. This adds extra strobe while panning and tilting. In 25p, 24p and 30p, this is much noticeable. In 60p/50p and 50i/60i, this is a non issue- maybe you can get a small tilt or jump from OIS compensation, but its not a major constant problem. I do not know how to give you a technical description of the effects in 25p or 24p, but the actual results are as I described. I would certainly be more than happy to post some footage about this.

R Geoff Baker · March 28th, 2007, 05:58 AM

If you could post footage, I'd be most interested in seeing it.

Cheers,
GB

Cole McDonald · March 28th, 2007, 10:44 AM

The only blurring I saw looked like de-interlacing artifacts...or slow-mo frame blending. Every couple of frames, the image seems to ghost...step through it and watch the edge of the license plate.

Sergio Perez · March 28th, 2007, 10:49 PM

Quote:

Originally Posted by R Geoff Baker

If you could post footage, I'd be most interested in seeing it.

Cheers,
GB

I'll do that. Need some days tough- going abroad for some event coverage, be back in a week.

Herman Van Deventer · April 1st, 2007, 12:34 PM

GONZAQUE,

If your problem is "shudder" related / try this link on motion / movement /
shutter / shudder etc.

http://hd24.com/dont_shudder_at_the_judder.htm

Herman.

Gonzague Alexandre · April 1st, 2007, 05:38 PM

Thanks, did not had time to play with my HVX lately, but will surely read !

March 26th, 2007, 01:53 AM	#20
Sergio Perez Major Player Join Date: Feb 2005 Location: Macau Posts: 331	If sound is not important, I would suggest shooting 30pn with 60p slowmotion. Than speed up in post (double speed). Shutter at either 125 or 250. Try this out. As for native 30pn, if you don't want the moving car to stutter, try Panning with the car CENTERED. The scenery will blur, but the car will stay sharp. Shutter speed of 125 should be the further you go. And do turn OFF OIS, like the fellow DVInfo member pointed out. OIS adds a layer of blur, EDIT much noticeable in FILM LIKE Progressive frame rates- 30p, 25p or 24p . It was designed to work in Interlaced modes, EDIT or smooth progressive frames like 50p or 60p, not in film like frame rate modes. __________________ If you don't believe in your film, no one else will. Last edited by Sergio Perez; March 26th, 2007 at 04:47 AM.

March 27th, 2007, 08:17 PM	#24
Sergio Perez Major Player Join Date: Feb 2005 Location: Macau Posts: 331	Mr Baker: Your description of the OIS system is correct, but what I mean by the "Layer of compensation" is what you describe. This adds extra strobe while panning and tilting. In 25p, 24p and 30p, this is much noticeable. In 60p/50p and 50i/60i, this is a non issue- maybe you can get a small tilt or jump from OIS compensation, but its not a major constant problem. I do not know how to give you a technical description of the effects in 25p or 24p, but the actual results are as I described. I would certainly be more than happy to post some footage about this. __________________ If you don't believe in your film, no one else will.

March 28th, 2007, 10:44 AM	#26
Cole McDonald Trustee Join Date: Nov 2005 Location: Sauk Rapids, MN, USA Posts: 1,675	The only blurring I saw looked like de-interlacing artifacts...or slow-mo frame blending. Every couple of frames, the image seems to ghost...step through it and watch the edge of the license plate. __________________ Web Youtube Facebook

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March 25th, 2007, 09:54 AM	#17
R Geoff Baker Major Player Join Date: Jan 2005 Location: Ottawa, ON Posts: 471	'Cannot' ... You can always use high shutter speeds when the subject is motionless. And in general, if the object is moving towards or away from you, you can use much higher speeds than if the subject is moving laterally. And if the object is distant, you can use a higher speed than if it is close ... As for the full digit rule ... I don't know where you are going with that. In general, shutter speeds are in full stop increments -- each notch halves the speed, and so drops the exposure by one full stop. But there is no rule in that -- if the speed dropped by less than half, the aperture would open a little to keep exposure accurate. 30/60/125/250/500/1000 is not essentially any different than 25/50/125/250/500/1000 ... the percentage 'jump' from 50 to 125 is mildly significant, but once done the rest of the values hold. HTH GB

March 25th, 2007, 11:06 AM	#18
Brian Drysdale Inner Circle Join Date: Feb 2006 Location: Belfast, UK Posts: 6,152	You're better using neutral density filters for controlling exposure rather than shutter speeds.

March 25th, 2007, 05:11 PM	#19
Gonzague Alexandre Regular Crew Join Date: May 2006 Location: Tokyo - JAPAN Posts: 43	Thanks Guy... I need to play more and to more test until I reach the perfect setting... unfortunately time is always my enemy... Once again Thank you for your kind help

March 26th, 2007, 04:28 AM	#21
R Geoff Baker Major Player Join Date: Jan 2005 Location: Ottawa, ON Posts: 471	Why would an 'Optical Image Stabilizing' system care if you were shooting interlace or not? What 'layer of blur' could the moving lens of the OIS system introduce? Turning off OIS to smooth panning makes sense, if the OIS is sensitive to the rate of pan ... but frankly, rest sounds like nonsense ... GB

March 26th, 2007, 05:21 AM	#23
R Geoff Baker Major Player Join Date: Jan 2005 Location: Ottawa, ON Posts: 471	Maybe nonsense is harsh -- I surely didn't mean to stifle discussion. But I fail to see how an optical lens, tilting in response to axis movement of the device ... can add a layer of anything. The lens tilts in and the image is respositioned on the sensors. The sensors, and the encoder, are 'dumb' to the action of the lens -- the reason to turn the system off during a pan is mechanical ... the tilt defeats the movement of the pan momentarily, then gives up and the image jumps to the new position, then the system tries to defeat the pan, et cetera. It is only because the OIS doesn't 'know' that you intend to move the image that it fights you. But try as I might, I can't make sense of the rest of your description of the operation of the optical image stabilizing system. It is blind to frame rates, it doesn't add layers of anything, it is a 'simple' optical mechanical device, rather like a tripod's fluid pan head ... and simply can't be responsible for the effects I understand you to be describing. GB

March 28th, 2007, 05:58 AM	#25
R Geoff Baker Major Player Join Date: Jan 2005 Location: Ottawa, ON Posts: 471	If you could post footage, I'd be most interested in seeing it. Cheers, GB

April 1st, 2007, 12:34 PM	#28
Herman Van Deventer Major Player Join Date: Nov 2006 Location: cape town South-Africa Posts: 251	GONZAQUE, If your problem is "shudder" related / try this link on motion / movement / shutter / shudder etc. http://hd24.com/dont_shudder_at_the_judder.htm Herman.

April 1st, 2007, 05:38 PM	#29
Gonzague Alexandre Regular Crew Join Date: May 2006 Location: Tokyo - JAPAN Posts: 43	Thanks, did not had time to play with my HVX lately, but will surely read !