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-   -   EX1 and flying birds (https://www.dvinfo.net/forum/sony-xdcam-ex-pro-handhelds/121618-ex1-flying-birds.html)

Steve Phillipps May 14th, 2008 01:12 PM

EX1 and flying birds
 
Been shooting a few tests with a loaner EX1, on panning shots of flying birds against hills/woodland backdrop the background does seem to show quite a lot of jerkiness, presumably the "skew" from the rolling shutter, does this sound the likely cause? Sorry I can't post clips, not geared up for it here. The bird stays sharp, but background is very distractingly jerky.
Steve

Steven Thomas May 14th, 2008 01:38 PM

Frame rate.

What frame rate are you shooting?

Steve Phillipps May 14th, 2008 01:54 PM

720 25/60 mostly. But on scenic pans at 1080 30P or 25P it also jerks, but less so as the pan's slower of course. You can see the jerkiness on the LCD as you do the shot.
Steve

Robert Young May 14th, 2008 05:08 PM

Try shooting the pan at 1080i and see if the jerkiness disappears.
To me, it always looks a bit "jerky" when I pan in 24p particularly, and less so @ 30p.

Tim Polster May 14th, 2008 08:44 PM

Yes, I would think the framerate is the most important aspect here.

Anything under 60i or 60p would have a tough time keeping up with a flying bird against a non-moving background.

To my understanding, the rolling shutter would show signs of bending of straight lines rather than jutter.

But I don't own the camera, so please correct me if I am wrong.

Craig Seeman May 14th, 2008 08:54 PM

Think about how sports are typically shot and televised. It's either 1080i60 or 720p60 (NTSC lands).

30p and even more so 24p call for SLOW panning. This is not specific to the EX1. It's the nature of temporal motion. Increase shutter speed and you further exaggerate the effect too due to less motion blur.

Serena Steuart May 14th, 2008 11:03 PM

Yes, a rule of thumb for panning a static scene at 24 fps 180 deg shutter is 7 seconds for an object to traverse the screen. Faster and it will be jerky. Three seconds for 60 fps. But if you are tracking a moving object, generally the audience isn't conscious of the background because it is blurred. However using a fast shutter that freezes the background will cause problems.

Steve Phillipps May 15th, 2008 01:56 AM

I'm used to seeing blurring on Siny 750 and Varicam types, but not judderring which is what this is, seems like it's having a job keeping up with refreshing the complex image.
As for frame rate, it really shouldn't matter - when you follow a moving bird in flight the bird can be sharp at 25P, it's just that its wings will be whizzing up and down so fast it's horrible to watch, and the background again should be blurred by the motion but steady.
Steve

Tim Polster May 15th, 2008 07:40 AM

Quote:

Originally Posted by Steve Phillipps (Post 877545)
when you follow a moving bird in flight the bird can be sharp at 25P, it's just that its wings will be whizzing up and down so fast it's horrible to watch, and the background again should be blurred by the motion but steady.
Steve

This depends upon the speed the bird is flying.

Try to shoot the same sort of scene with 60p and report back to the forum.

I would like to hear the results.

Craig Seeman May 15th, 2008 07:43 AM

What was shutter speed/angle?

I was shooting tennis players running up and down court (hence fast panning to follow the players) and had no judder problem at all. This was at 180. Go to a faster shutter speed/smaller angle you'd certainly get the "Private Ryan" look but you'd know that.

Dave Morrison May 15th, 2008 08:08 AM

Would it be helpful to anybody else (including ME!) if some of you folks could post some good examples of "judder"....maybe make it a Stickie so we have it always available. Actually, it would be great to have a permanent collection of ANY of the common image problems associated with the EX1 so we are "on the same page". I remember one posting from a few weeks ago showing some "bad" pans but it would be great to have some really solid examples of these anomalies. If this has been done already, I'll shut up. ;)

Steve Phillipps May 15th, 2008 08:11 AM

I was shooting at 60, with 180 degree shutter as normal. As I said, it's not the bird that's juddery, it's the background, the bird is not changing its position in the frame as I'm keeping it central so it's sharp and stable, but of course the background is whizzing along.
Steve

Craig Seeman May 15th, 2008 08:23 AM

That's why I made note of my tennis shoot. Same thing. Tracking the player but the background did not judder for me. I did see the rolling shutter skew on the background but no judder at all.

Maybe you can post a hi rez example on Vimeo.

Quote:

Originally Posted by Steve Phillipps (Post 877662)
I was shooting at 60, with 180 degree shutter as normal. As I said, it's not the bird that's juddery, it's the background, the bird is not changing its position in the frame as I'm keeping it central so it's sharp and stable, but of course the background is whizzing along.
Steve


Steve Phillipps May 15th, 2008 08:39 AM

If you saw skew, then I guess that's what I'm seeing too, whatever it is it's not pleasant, makes your eyes go funny after a short time!
Steve

Craig Seeman May 15th, 2008 08:49 AM

Although the skew is very different than judder. Skew is smooth as silk. Background begins to bend as one starts fast pan and straightens out at end of pan. It's currently the nature of CMOS. Red camera has this too.

Given the shots I see it on I think it adds dynamism. The background bends but the subject is fine. Gives a sense of motion and speed to the shot. If you really find it objectionable than CMOS just isn't a good solution for you. Again none of this looks like what I'd call judder (which to me is uneven or "stepped" motion).


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