Rolling Shutter CMOS Artifacts

3xm said:
I maybe mistaken but the problem is not with fast moving objects but rather with a fast moving camera....such as a pan...that's when the wobble occurs....
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right... with the exception of the fast moving object itself being subject to wobble/skew.

The reason there is wobble/skew is because of a rolling shutter.


If you pan past a pencil fast it will skew right?

My hypothesis would be that if you move the pencil instead of the camera at the same relative rate through the frame it will have the exact same amount of skew as if you panned fast.

The whole frame wouldn't wobble but the pencil would skew due to the partial exposures inherent with a rolling shutter.
 
ESTEBEVERDE said:
My hypothesis would be that if you move the pencil instead of the camera at the same relative rate through the frame it will have the exact same amount of skew as if you panned fast.

The whole frame wouldn't wobble but the pencil would skew due to the partial exposures inherent with a rolling shutter.
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Of course, for sure.
 
It has nothing to do with camera movement, per se. It is only as to do with the movement of the subject relative to the camera. I could take a photograph (or a pencil) and move it in front of a static camera and the distortions would be the same.
 
Yes, that's just what ESTEBEVERDE was saying.
It' s movement across the image plane regardless what's moving, the senor relative to the image, or the image relative to the sensor.
 
I still like this cam!

I mean shoots.

If red is good enough for the big boys, shouldn't the little ol EX1 be good to me?


My last hold up is the loss of res when panning.


Guys if you have the cam... how about working it out a bit and posting some footage of pans and what nots?

If it's not to much trouble. :beer:
 
The only way would be for someone to post the same pan using a different camera. Ideally the other camera would have a global shutter like the HVX200.

Even then, since some may feel it's the codec creating a loss of detail. I certainly don't believe the EX1 35mbps HQ codec would fail. The softness that was refered to by Barry was real time off the head.

I still go back to - If it's a fault the image processing not having the response speed, then why does it improve with shutter speed.
 
I am becoming more convinced that there is absolutely nothing to the "resolution loss while panning" silliness. I'm preparing a test that I will try to post tomorrow - It just needs daylight to complete so I'll get to it in the morning.
 
One interesting thing to observe on the EX1 (and this may be true of other cameras - I don't know) is that peaking finds vertical lines of contrast. If you pan, the peaking goes away because motion blur smears the vertical lines and reduces their contrast.

If you *tilt* on the EX1, you will see that peaking does not change - no "resolution loss" occurs.

Also, if you tighten the shutter to 1/2000, peaking is unaffected by normal panning, ergo, no "resolution loss" is likely to be occurring.
 
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Interesting. Now that you mention it, I do recall noticing that the peaking only disappeared on the horizontal. We noticed the res difference on the horizontal, not on the vertical. Motion blur should be equally applicable to both the horiz and the vert.
 
I would guess that motion blur is the same for both horizontal and vertical (except for minor differences due to vertical shutter scan) but that it is the peaking that is inconsistent. Peaking seems to find contrast in the vertical features and not horizontal features.

If you place a resolution chart in front of a static EX1 you will see peaking all over the vertical stripes but no peaking whatsoever on the horizontals.
 
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O.K.

I fully admit I am the slow one on the short bus.

If it's not to much trouble, could a few of you describe a bit more about the peaking. I don't quite get it.

Do you mean peaking as far as hot exposures in the frame or???
 
Peaking is a focusing aid built into the EX1 (and similar to the focus assist function in the JVC cameras) that finds contrasty edges in the frame and applies a color to them. It allows you to see things "snap" into focus more easily.

On the EX1 it finds vertical contrasty edges (abrupt changes in luminance along the horzintal raster lines) and does not seem to find horizontal edges.
 
matthew77 said:
I would guess that motion blur is the same for both horizontal and vertical (except for minor differences due to vertical shutter scan) but that it is the peaking that is inconsistent. Peaking seems to find contrast in the vertical features and not horizontal features.
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It should find it on vertical as well. Even so, the res loss that we were noticing was on the waveform monitor, not the cam's LCD. I brought up the peaking only to show people that it's obvious to see that something's happening, and that same effect doesn't happen on other cameras that I've tried (at the same pan rates, etc... obviously if you use an excessively short shutter speed or move excessively quickly you can force it).
 
But Barry, the EX1's peaking clearly only works on verticals - if you don't believe me try what I said - use a res chart and see if peaking appears on the groups of horizontal lines. It doesn't.

This is with a static camera.
 
Here's a test I did to check for resolution loss when paning the camera. It is not a perfect test but in any case reveals no change at all in a panning or still camera.

The chart is attached to the matte box. DoF was not enough to get it all in perfect focus.

These 1/4 size are crops but have not been resampled (except for jpg). The majority of the frame (not shown) is a panning image.

If there is any way I can improve this test and reshoot it, I would be happy to do so. Suggestions welcome.
 

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