Rolling shutter Jello

[Don]

Am I correct that increasing the FPS will reduce the Jello effect that rolling shutters produce when there's motion in camera's FOV?

Are there any other ways to combat the Jello effect other than dealing with it in post-processing?

Thanks!

[humptybump]

Increasing the FPS will not significantly aid with the "rolling shutter" problem. The issue is a byproduct of how the vast majority of low-cost POV cameras work (CMOS technology). Rather than capture a frame at a time, they capture a scan line at a time. The result is the image composition can change between scan lines at the start of the frame relative to the bottom.

"jelly" is caused by vibration while "warping" is caused by objects moving quickly.

You can reduce the jelly effect by reducing vibration - specially at key frequencies.

[DougJ]

humptybump, great explanation of the phenomenon, makes sense. I recieved a Gopro as a gift for Christmas and have seen this already, now I have some understanding of it so perhaps I can combat the issue.

Thanks!

Doug

[Low Pass]

What Jello effect are you talking about? The one I'm familiar with happens to the whole image when the camera moves or vibrates. In that case, you need a more rigid mounting system.

[humptybump]

Bryan - most occurrences of the "jelly" effect are related to vibration and most of the vibration is from the engine.

One thing I still have not done if go out and fly at a series of engine RPM while recording so I can see which settings cause the most/least effects.

Since every aircraft is different, with different resonance, and different camera mounting positions, I don't think any one aircraft's data will help any other aircraft.

[Low Pass]

Originally Posted by humptybump

Bryan - most occurrences of the "jelly" effect are related to vibration and most of the vibration is from the engine.

One thing I still have not done if go out and fly at a series of engine RPM while recording so I can see which settings cause the most/least effects.

Since every aircraft is different, with different resonance, and different camera mounting positions, I don't think any one aircraft's data will help any other aircraft.

I've had great luck using a three-legged RAM mount system. Suction cups (RAM items) attached to a camera work well in many locations on the plane. Zero jello. And very secure installation (if a glossy/smooth surface for the suction cups). Pic shown has a screwed ball at the aft location (for use in the tie down).

[Don]

Originally Posted by Low Pass

What Jello effect are you talking about? The one I'm familiar with happens to the whole image when the camera moves or vibrates. In that case, you need a more rigid mounting system.

Lowpass, It is definitely not the whole image. It's mostly in the bottom left side of the image and its a waviness like you'd get looking through warped glass. Which means it may be warping, per humptybump's explanation.

The mount I'm using is exactly like the one PerfTech shows here: http://www.vansairforce.com/communit...3&postcount=29 (except mine is on the left wing). It seems very solid but I'm open to ways to improve it.

In any event, my interest is in reducing or eliminating the flaw with the least amount trial and error. If the mount is the problem there's no sense in trying different camera settings and engine RPMs, etc. So I guess the first thing is to figure out if what I have is a 'jello effect' or 'warping'.

[flyboy1963]

I'm certainly no authority, but there's lots of possible improvements...here's one of the better explanations I've found.

http://flitetest.com/articles/vibrat...uses-and-cures

Increasing the frame rate, or using filters seems to be the basic solution path, depending on your equipment. Try duct taping an old sunglass lense over the camera lense, and see if it improves it; let us know how things work out!

[humptybump]

The use of a neutral density filter changes the shutter speed and hence it changes at which vibration frequency the "jelly roll" effect occurs.

What is interesting is that increasing the frame rate and adding an ND filter would be counter producing results - one is speeding the shutter rate and one is slowing it.

[flyboy1963]

Originally Posted by humptybump

What is interesting is that increasing the frame rate and adding an ND filter would be counter producing results - one is speeding the shutter rate and one is slowing it.

...by sheer fluke I said 'frame rate 'OR' filter.....' but that's easy to miss, thanks for that clarification Glen! ( 'speshully for those of us who don't really know WHY things work, but use the trail & error method!)