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My Tips on Getting Jello-Free Video wtih GoPro 3

Discussion in 'Photos and Video' started by jp3556, Sep 11, 2013.

  1. jp3556

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    Maybe this should have been a response to an existing thread, but wanted to summarize what I learned over a few months of trial and error with my Phantom and GoPro 3 to achieve jello-free video.

    1) Buy some Sorbothane

    I got a sheet of 3/16" x 12" x 12" 'IsolateIt!' brand from Ebay. Unfortunate that you have to buy it in sheets so large, since you only need about a square inch - best to pool with a few other Phantom owners on this since it's around $50-$100 per sheet!

    EDIT: As @FangsCPO points out below, you can buy smaller pieces of this from drum/music shops.

    It comes sticky on both sides, but not sticky enough so I used a couple of the sticky pads that I'm pretty sure came with the Phantom.. If not, then I can't remember where I got them from. I originally tried two layers doubled-up, but it was unnecessary and made it too wobbly. I made a light-weight anchor, tying the stock mount to the frame with string just in case. But note, you shouldn't use screws at all since they'll transfer vibration to the camera.

    (tried to upload an image but it's "over limit", sorry)

    2) Use ATTI mode

    Sure, the Phantom tends to drift in ATTI mode, especially in light wind. But as long as you learn to work *with* the wind and not rely on the GPS to fight it, the movement should look more natural than the jerkiness you tend to get from the GPS constantly correcting itself.

    In fact, if you don't have a gimbal then you may want to get it going for something like a side-tracking shot and then just let it continue to drift fluidly with its own momentum and without pitching to the side.

    3) Shoot at 60 fps 1080p

    You want to shoot at 60 fps, which I believe will force the camera to shoot at a shutter speed of 120 instead of 60 for 30 fps - at least this is the way you normally do the math on a regular pro video camera, shooting at least double the frame rate to achieve 'normal' motion blur.

    You can then choose to either speed it back up a percentage in post or leave it at slow-motion for a more cinematic-feel (probably best to split the difference).

    Of course leave the WiFi off to avoid interference (it's a delayed image anyway), and shoot on ProTune if you have the ability to do color correction in post - this will help with the camera's limited contrast range.

    4) Stabilize with Warp Stabilizer and correct lens distortion

    If you have it available, use the Warp Stabilizer filter in either Adobe Premiere or After Effects. It will zoom in and crop the image a bit, but since we've shot in 1080p there should be plenty of resolution to spare so that you can still achieve a full 720 resolution on your final image.

    Depending on how much you had to stabilize, you should still have enough left over resolution to correct the lens distortion by the GoPro as well and flatten out that horizon. I personally can't stand the GoPro fisheye look.

    EDIT #2: I realized I forgot to mention balancing your props! Really important, although pretty obvious I suppose.

    I'll be getting the new DJI Zenmuse gimbal in the next few weeks and hopefully a FPV setup of some sort, so the Sorbothane will actually be coming off - really looking forward to being able to tilt the camera too. Anyone have any other tips to add?
     
  2. FangsCPO

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    Location:
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    Great tips!

    You do realize you can by Sorbothane already cut into little squares from most music stores. I believe that's the same thing drummers use. It will cost you about $7.
     
  3. jp3556

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    @FangsCPO well that would have been a lot cheaper for sure ;). I had called around to a bunch of appliance repair places, since they use sorbothane in fridges to reduce vibration, but I didn't realize they used it for drums too.

    @justsomeguy that isolation mount looks pretty good. Not sure they had those back in Feb. when I started researching, but I'm personally moving to a gimbal system as I mentioned anyway - best bet if you can afford one where stability is concerned.

    With a gimbal, you're right, you'd almost not have to worry about stabilizing at all, just doing barrel correction. To clarify though, I found that an increased shutter speed was beneficial (eg. 120 or higher instead of 60), whereas using ND would cause the shutter to slow in an effort to allow for more light in order to compensate. Although in bright light, yes you'd want to further cut it down using ND (that's a little more advanced though).

    But do you find the end results at 30 fps in 2k are as good as at 60 fps in 1080p, aside from the obvious benefit of being able to master in 1080p? I'll have to try a comparison of each, rendered to 720p..
     
  4. jp3556

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    @justsomeguy well of course FPS is not the same as shutter speed, but they are related.

    Shutter speed cannot be slower than the number of framers per second. Eg. you can't have a shutter speed of 30 while shooting at 60 fps. You normally want to shoot at roughly double the shutter speed of your frame rate to achieve 'normal' motion blur - less than this will create a strobe, and too high of a shutter will give you Saving Private Ryan.

    So my only point was that I suspect by shooting at a faster frame rate, you force the GoPro into shooting at a faster shutter speed as well, thereby decreasing the amount of rolling shutter effect that is often seen in aerial video. An ND filter would have the opposite effect.
     
  5. jp3556

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    @justsomeguy glad to have the results of your own experience added to the thread.

    I still personally enjoy the look of video that has at least been slightly slowed down by filming at 60 fps 1080p vs 30 fps 2k, but to each his own. I suppose that one last option is always to shoot 30 fps and master in 24 fps which will give you a bit of slow-motion.
     
  6. Roadkilt

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    I have found that flying backwards, ie start close to target and pull back gives me the best video. The props tilt up out of the frame, you know exactly where the phantom is coming from so steering is not zig zaggng around, you can maintain a constant speed so there is less fish eye from horizon movement and wander, and best of all the bird is coming back to you! If I can I set home point at my feet, then walk the few hundred meters away , set the quad down, walk back, then start up, hover to my shooting height, and pull the sticks so its a straight line backwards. Makes for excellent jello free video. I'll sometimes reverse it in editing so it actually looks like it went forward if that's the shot I wanted. Try it!
     
  7. Roadkilt

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    Those 2k video files are a pig on my computer to edit and render, and its a two year old MacBook Pro, forget the 4k. Unless you have the horsepower to run editing software with huge files I would stick to 1080.
     
  8. jp3556

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    Nice one, really seems to help with the 'prop flutter' as well. Think I'm going to have to get myself a pack of these..
    You're right, if you're doing longer flights and not shooting for a more professional project, 1080p is totally sufficient.
     
  9. martcerv

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    The sorbothene I have heard a few people recommend, I havent tried it myself yet as I use a carbon fiber rubber grommet isolation mount. I have tried a couple of these with one from VGE first but found the grommets a bit too soft and ended up breaking it in a crash. Now I use one from helipal, it has stiffer grommets and works ok.

    I think the most critical thing you missed is balancing props. Get a good balancer like the dubro and you can get any decent props pretty smooth. Vibration isolation Is also critical but I dont think there is any one thing that gives best results but a combination of them all.

    I also use ND filters on the SRP adapter and these help out on the bright days. But I found when altering my mount for my 3d setup that I had the camera flopping in the wind a little and I got pretty bad jello. This was even though I had balanced props, the anti jello mount and nd filters. So even if you get most of it right one thing being out badly will ruin your video but you need to do the best you can with each aspect for the best jello free video especially when its bright and sunny.

    I have sorted that camera mount issue now can get pretty much jello free footage in any mode or light using balanced motors and props, anti jello mount plus a stiff way of attaching cameras to this. Then using ND filters to top it off, I tried the cheaper polar pro filters but didnt like the results, washed out the image and bad reflections in bright sun when you need it most.

    Here is some flying in bright sun shot in 1440p30 on the h3b. Tiffen nd.9 used in nearly all shots the one high **** before the 2 laps was a nd.6 and showed more jello with the faster shutter speeds.

    No software correction here other then basic colour grading and cropped to 1080p and moved the frame up to show more then just the ground at the fairly high pitch angles here.

    [youtube]http://www.youtube.com/watch?v=FQHY5zXXk5E[/youtube]
     
  10. jp3556

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    Yep, I had added that as an edit after the fact, but you're right. Seemed like such an obvious thing at the time, but I suppose it's not.

    I guess you could even upgrade your props to those carbon ones, although I didn't find that was necessary. The stock plastic ones can sure take a beating, too ;)
     
  11. howardmaryon

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    Just a point about video quality and shutter speeds. Very fast shutter speeds (not frame rates, thats different) create a series of very sharp still frames, which when played back can exhibit a nasty optical effect called "stroboscoping" or strobing for short. This gives the video a stuttering effect that is very tiring to look at. Pro cinematographers carefully control their shutter "angle" by using nd filters to keep the exposure times relatively long, around 60th of a second if possible. This allows a little blurring of moving subjects which gives a pleasing "cinematic" look to video. You can buy filter adapters that take standard 52mm camera filters or square plastic "cokin" type filters to fit on a gopro hero3, so you can use 2x, 4x or even 8x neutral density filters depending on the light conditions.
     
  12. martcerv

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    That is one of the main reason I use an ND of some power for nearly all flights depending on the lighting at the time. From ND2 to ND8, the cokin filters will work quite well but the other reason I like to use the 52mm Blurfix micro is that it also gives some protection to the naked lens. Even when not flying a filter I will chuck the blurfix on as this will take the impact most likely instead of the round lens as this is now set behind the outer edge of the filter adapter.

    The gopro is a fixed aperture lens camera and so the only way it controls exposure is by shutter speeds, one of the things I hate most is shooting very high shutter video then playing it back at 100% speed at 24-30p as it gets that stroboscopic movement. Slowing shutter with ND filters or simply filming in low light will give some nice motion blur and make the video play much smoother. Still frames will look crappier obviously but if your shooting video motion blur is nice, for photos sometimes its nice other times you want very high shutter crisp images. If you have no motion blur going on it simply looks like a series of still pictures and any panning or fast motion will make the movement not smooth at all.

    Here is an example of extremely slow shutter gopro video, this was shot just after sunset with no filters and so there is also video noise here. I am quite amazed that it looks this good still as it was so dark that I really couldnt see anywhere near as much as in this video. As its so dark there is a slight red tint in the corners off the LED's and you can also see the street lights in the background and sun has already gone below the horizon. This shows the extreme end though as this is very low light and shutter speed will be the slowest possible at double the frame rate which is generally the target. But the low light has also upped the ISO and gain so much more noise in the image. You want to try and use a filter that gets your shutter speed down to double your frame rate so 1/60th at 30p but not to a point where it needs to up the ISO due to very low light.

    [youtube]http://www.youtube.com/watch?v=924q5Irfyn8[/youtube]

    In terms of Jello and shutter speeds, Jello is caused by the rolling shutter sensor which scans top to bottom during the frame capture. If the camera has many tiny vibrations in this time the camera will move up or down a pixel or 2 between the start of the frame capture and the end of the capture which means some parts of the frame have either moved up or down during this process. Then the next frame it will do the same and so you end up with wavey video which is the biggest negative point of rolling shutter CMOS sensors. The better the light the faster the shutter speed and the crisper the image but also the more it shows this motion between start and end of the frame capture if you have very high frequency vibrations that shift the image a few pixels up and down during the capture process.

    What slowing shutter speed does is it will give a longer exposure time but the scanning process will still be at the same speed, so the extra exposure time will end up causing a blurring effect as the vibrations move the camera up and down a few pixels. Ideally you would want a perfectly still camera so you get no blurring due to vibrations only the preferred motion blur, though I prefer this over rolling shutter jello any day. The older CCD type sensors have global shutters so they capture the entire frame at once and no top down rolling scans so jello is not an issue but if its vibrating a lot the video will still get very blurry.

    The GoPro hero4 possibly may be a global shutter camera so it would avoid this and be a huge plus for gopro if they can pull it off, but its still unlikely to be in the next gen and we may need to wait another 12 months till this makes it into the small action cam market. But even if jello wont be an issue you will still want slower shutter speeds in bright light to avoid the strobe effect this gives to motion at very high shutter speeds with video playback at 100% speed at 30p or slower.
     
  13. yalag

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    Hey there seems to be conflict, some say faster shutter speeds (by increasing the FPS), some say slower shutter speed (by using a ND filter). Which is correct for less jello?
     
  14. jp3556

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    My own experience speaks to using faster shutter speeds, but it seems that most have found the opposite - so safe to say slower with an ND filter is the way to go.
     
  15. yalag

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    They are different things but related. By increasing the FPS, I'm expecting the shutter speed will be increased by the GoPro (usually kept as double of the FPS). So it's conflicting with the ND strategy.
     
  16. jp3556

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    Yes, but since again you have no control over manual shutter speed on the GoPro, one way to control it may be by using frame rate. They are linked in that shutter typically cannot be slower than frame rate without strobe - I doubt the GoPro allows for this, therefore a frame rate of say 60 or 120 would mean a minimum of 120 or 240 shutter.
     
  17. jp3556

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    Exactly. So your question is, which provides better results - faster shutter speed or slower shutter speed, either being achieved by using ND (to slow it down) or frame rate (to hopefully speed it up). My very limited tests seem to conflict with the others here so I'd assume using ND to slow down the shutter is the way to go.

    Rolling shutter due to CMOS chips: http://www.diyphotography.net/everythin ... ng-shutter
     
  18. hhstefan

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    Luftaufnahmen vom UFO & Aerial photographs of the UFO

    [youtube]http://www.youtube.com/watch?v=oi3B81TBG-0[/youtube]
     
  19. hhstefan

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    Potato Crop 2013 mit DJI Phanom and Gimal


    [youtube]http://www.youtube.com/watch?v=dWyJbOWJF4c[/youtube]
     
  20. hhstefan

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    [youtube]DJI Phantom : Hafencity Elbe Philharmonic Hall in Hamburg with[/youtube]