Just an observation on the movi M15

Discussion in 'MōVI M15' started by Adam Brennan, Mar 9, 2017.

  1. Adam Brennan

    Adam Brennan Member

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    I used to use a Canon 1DX and some heavy glass with my Movi M15 and M10 set up. I would say with camera and lens with redrock gear follow focus, it all weighed about 7 pounds. I get everything balanced and auto tune it. I always seem to get video footage that was not always smooth or stable. Fast forward, I buy a Red Epic W with glass and gear set up. I would say it weights 10-12 pounds. Balance the rig and my video footage has is so much smoother and stable now. Nothing like before. So my question is does the weight of the camera make a difference in getting better & smoother footage?
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I'm not sure I can answer your question directly, Adam, but as a general truth the "mass-in-motion" certainly affects the gimbal's performance. For example, if you were to put an iPhone on an M5, it's too light for it the gimbal to work well. You need to add mass.

    The other major factor, of course, is the tuning values -- get them wrong and, with a lighter camera, I suspect you're more likely to see the negative effects more easily just because the motors can move the mass-in-motion more easily and can vibrate/oscillate more easily. So a heavier camera can mask some tuning errors because it has more inertia and dampens down some vibration/oscillation.

    Hope that helps. I did say it wasn't a direct answer, didn't I?
    :rolleyes:

    Andy.

    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
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  3. Adam Brennan

    Adam Brennan Member

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    Thanks Andy for taking the time to write. Someone told me the Autotune feature may be set to high from the factory a little too high for a DSLR weight camera? I am usually at 70% Autotune %. Do you just rely on Autotune or do you go beyond that when tuning? With my Red Epic W camera on the movi m15, it just seems near perfect in the smoothness.
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Adam: Autotune is an excellent place to start but I use the "trust but verify" approach. I think of Autotune as "Ballparktune." :)

    So I'll certainly start with Autotune with the MoVI held/mounted exactly as I'm going to use it (e.g. handheld or suspended under an ALTA hung from the ceiling if airborne). But then I'll move the MoVI around a bit to exercise it and see if I can detect (either audibly or with a fingertip resting on the carbon fiber) any kind of vibration/oscillation. You can also see it on the iPhone/iPad/Android app's Monitor/Charts as a nice jaggy line when there's vibration/oscillation. With handheld it's pretty easy to hear/feel the vibration/oscillation too. The most sensitive means is the app's Charts.

    If vibration/oscillation happens at any point I'll crank the stiffness settings down a unit or two and try again.

    In every sense of the words, it's a "balancing act" -- the Autotune (as far as I know), waggles the MoVI/Camera back and forth and then reads the data from the accelerometers to see how the motion decays and makes adjustments accordingly.

    But it's imperative you tune it as you intend to use it otherwise you feed the Autotune bogus information about how the mass-in-motion is responding. If you do make any manual adjustments after Autotune, make only small changes as you can blow past the sweet spot if you make big changes.

    Hope that helps.
    Andy

    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Afterthought: The "tune it as you are going to use it" means if you're going to run with it using just the top-handle then that's how you tune it. If you're going to hold it with both hands -- then hold it that way when you tune it.

    Andy

    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  6. Adam Brennan

    Adam Brennan Member

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    Thanks Andy! You're a great resource to this site.
     
  7. Jason Comparetto

    Jason Comparetto Active Member

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    I'm surprised Andy is the only one who responded here. This is a very interesting finding. Perhaps Andy's responses were more than enough to answer to question. I just wanted to throw in a few ideas:

    1) Almost all physical machines have a *sweet spot*. The Movi's would not be an exception. And as Andy has pointed out, due to inertia objects with more mass tend to be more stable.

    2) The mass distribution would also have an impact. Example, a 10 lb sphere with an homogenous density would spin quite freely in space, where as a long rod with 2 balls each weighing 5 lbs on each end would be much more stable in space. despite both of them having the same exact mass. its quite possible depending on the lens and camera combo that the inertia characteristics could have been affected.
    Ok, here is a more formal physics explanation: " conservation of angular momentum"
    a physics video explanation from my favorite example-- figure skating:

    3) if any of Adam's observations are true, this would be very important for those of us who are trying to achieve an even more stable picture. We may just need to add a bit of weight, despite what that might do to our biceps :)
     
  8. Juan Lima

    Juan Lima Member

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    Weight and mass matters. The key factor is inertia. Inertial balance will affect any stabilizer system. A longer mass has different reaction than an shorter one no matter the same weights. So is important to use autotune as a starting point but find the sweet spot manually for every case.
     
  9. Augusto Alves da Silva

    Augusto Alves da Silva Active Member

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    That is my experience. Heavier cameras work better with bigger gimbals. I realised that if I go close to the weight limit of thew Movi it is much smoother and stable
     

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