Background
I have been fighting with a persistent jello problem for about 2 weeks now. In case you are not familiar with it, jello is the wavy appearance that shows up in video when a camera with a rolling shutter and a CMOS sensor is subjected to high or low frequency vibrations as it is filming. My jello problem was very intermittent and barely detectable but I'm a bit of a perfectionist so I refused to settle for anything less than jello free video.
I have a DJI Phantom 2 with the H3-3D gimbal and started out with a GOPRO HERO 3+ Black edition.
Things I Tried That Did Not Work
Gain Settings - Plenty of discussions around jello referenced gain settings so I tried various gain settings. None improved the situation and most had some other undesirable side effect (i.e. not flying straight, drifting at hover, slowly dropping, etc). In the end I went back into the DJI Assistant software and selected Default.
Different Bushings - The H3-3D shipped with 4 sets of bushings, with the recommended bushings being the white ones and the rest being different levels of firmness vs. the white ones. I tried the harder ones and it made it worse, I tried the softer ones and the whole gimbal shook so bad it was hitting the underside of the Phantom. So in the end I went back to the white bushings.
Prop Balancing - I tested the balance on all of my props and they were all already balanced. Just to be sure I went through 4 sets of props to see if it made a difference, my conclusion was that it was not the props.
Motor Balancing - I took the props off and ran the motors at full speed without the props attached. The Phantom was rock solid no vibration whatsoever so I concluded the motors were properly balanced.
Flying Slower - Some users have reported they only get jello at higher speeds so I tried flying slower. Certain maneuvers still resulted in jello no matter how slow I flew.
Things I Tried That Helped
Gel Insoles - I saw in a YouTube video that some users had had success with putting dampening material between the H3-3D gimbal and the Phantom's underbody. So I tried a few different types of materials and found the one that helped the most was a gel insole. I cut the insole to the shape of the H3-3D mount and cut out a hole for the middle of the insole for the gimbal to fit through then used slightly longer 3mm screws to screw the gimbal back on. Afterwards you will need to do an advanced IMU calibration so that the gimbal can compensate for the new addition.
Make sure you check the clearance between the bottom of the gimbal and the ground after adding any material like this. I started out with an insole that was too thick and the gimbal hit the ground on landing because it was slightly lower than the landing skids.
60FPS Frame Rate - The gel insoles eliminated about 95% of my jello but there was still a tiny bit remaining that would show up occasionally. I was able to eliminate 99% of my jello by increasing the framerate on my GOPRO HERO3 Black camera to 1080@60FPS. The problem with this is that I always take a picture every 5 seconds while recording so that I don't have to fly twice...once for video then a second time for pictures. The problem is the GOPRO HERO3 Black will only take pictures and record video simultaneously at 30FPS - which is where I was encountering the jello.
GOPRO HERO4 Black - I was FINALLY able to eliminate 100% of my jello with this camera. I noticed in the HERO4's specs that it would shoot 720P@60FPS and take a picture every 5 seconds; something the HERO3 Black could not do. So I got the camera thinking I would settle for 720P as long as @60FPS I would have jello free video and a picture every 5 seconds.
As a baseline I decided to take the HERO4 up in the Phantom and shoot at 1080P@30FPS + Picture every 5 seconds just to make sure the jello was the same before moving to 720@60FPS. Much to my surprise even though it was shooting at the same frame rate as the HERO3, the video was 100% jello free. The only thing I can figure is that since the processing speed of the HERO4 is 2x the speed of the HERO3 maybe the rolling shutter processes the image 2x as fast as the HERO3 - effectively halving the CMOS exposure time without actually increasing the frame rate.
Wrap-Up
If you have unbalanced props or motors I do not think gel or the HERO4 will fix your jello, but if you have eliminated every other source of vibration and have reduced it to the least amount of jello possible, then you may want to try the HERO4 if you are still not satisfied. I'm not certain I still need the gel insole between the gimbal and the Phantom, but my setup right now is so perfect I don't want to risk changing anything.
I have been fighting with a persistent jello problem for about 2 weeks now. In case you are not familiar with it, jello is the wavy appearance that shows up in video when a camera with a rolling shutter and a CMOS sensor is subjected to high or low frequency vibrations as it is filming. My jello problem was very intermittent and barely detectable but I'm a bit of a perfectionist so I refused to settle for anything less than jello free video.
I have a DJI Phantom 2 with the H3-3D gimbal and started out with a GOPRO HERO 3+ Black edition.
Things I Tried That Did Not Work
Gain Settings - Plenty of discussions around jello referenced gain settings so I tried various gain settings. None improved the situation and most had some other undesirable side effect (i.e. not flying straight, drifting at hover, slowly dropping, etc). In the end I went back into the DJI Assistant software and selected Default.
Different Bushings - The H3-3D shipped with 4 sets of bushings, with the recommended bushings being the white ones and the rest being different levels of firmness vs. the white ones. I tried the harder ones and it made it worse, I tried the softer ones and the whole gimbal shook so bad it was hitting the underside of the Phantom. So in the end I went back to the white bushings.
Prop Balancing - I tested the balance on all of my props and they were all already balanced. Just to be sure I went through 4 sets of props to see if it made a difference, my conclusion was that it was not the props.
Motor Balancing - I took the props off and ran the motors at full speed without the props attached. The Phantom was rock solid no vibration whatsoever so I concluded the motors were properly balanced.
Flying Slower - Some users have reported they only get jello at higher speeds so I tried flying slower. Certain maneuvers still resulted in jello no matter how slow I flew.
Things I Tried That Helped
Gel Insoles - I saw in a YouTube video that some users had had success with putting dampening material between the H3-3D gimbal and the Phantom's underbody. So I tried a few different types of materials and found the one that helped the most was a gel insole. I cut the insole to the shape of the H3-3D mount and cut out a hole for the middle of the insole for the gimbal to fit through then used slightly longer 3mm screws to screw the gimbal back on. Afterwards you will need to do an advanced IMU calibration so that the gimbal can compensate for the new addition.
Make sure you check the clearance between the bottom of the gimbal and the ground after adding any material like this. I started out with an insole that was too thick and the gimbal hit the ground on landing because it was slightly lower than the landing skids.
60FPS Frame Rate - The gel insoles eliminated about 95% of my jello but there was still a tiny bit remaining that would show up occasionally. I was able to eliminate 99% of my jello by increasing the framerate on my GOPRO HERO3 Black camera to 1080@60FPS. The problem with this is that I always take a picture every 5 seconds while recording so that I don't have to fly twice...once for video then a second time for pictures. The problem is the GOPRO HERO3 Black will only take pictures and record video simultaneously at 30FPS - which is where I was encountering the jello.
GOPRO HERO4 Black - I was FINALLY able to eliminate 100% of my jello with this camera. I noticed in the HERO4's specs that it would shoot 720P@60FPS and take a picture every 5 seconds; something the HERO3 Black could not do. So I got the camera thinking I would settle for 720P as long as @60FPS I would have jello free video and a picture every 5 seconds.
As a baseline I decided to take the HERO4 up in the Phantom and shoot at 1080P@30FPS + Picture every 5 seconds just to make sure the jello was the same before moving to 720@60FPS. Much to my surprise even though it was shooting at the same frame rate as the HERO3, the video was 100% jello free. The only thing I can figure is that since the processing speed of the HERO4 is 2x the speed of the HERO3 maybe the rolling shutter processes the image 2x as fast as the HERO3 - effectively halving the CMOS exposure time without actually increasing the frame rate.
Wrap-Up
If you have unbalanced props or motors I do not think gel or the HERO4 will fix your jello, but if you have eliminated every other source of vibration and have reduced it to the least amount of jello possible, then you may want to try the HERO4 if you are still not satisfied. I'm not certain I still need the gel insole between the gimbal and the Phantom, but my setup right now is so perfect I don't want to risk changing anything.
lol
