Super bumpy in the wind: OK?

Discussion in 'Cinestar 8' started by Steve Maller, Jan 21, 2013.

  1. Dan Coplan

    Dan Coplan Member

    Joined:
    Aug 8, 2012
    Messages:
    83
    Likes Received:
    1
    Has anyone successfully flown a Canon T2i resulting in stable video? I've gone through hours upon hours of testing with my CS8/3-axis carrying a T2i with Nikon 24mm (using Canon adapter ring) and have yet to achieve any video I would consider usable. This boils down to one or more of three conclusions: the Radians are bad, the servos are bad, and/or the T2i simply isn't a good camera to fly. However, I get pretty stable footage when the Radians are powered off which leads me to believe it's not the camera or the copter itself.

    My latest gain adjustments succeeded in reducing chatter but were too low to allow the gimbal to keep up with the copter movements so I either get a gimbal that keeps the video level but chatters like hell or relatively smooth performance but the video rocks left and right and front to back.

    Is it at all possible that there's a minimum weight requirement for the gimbal and the load I'm carrying is too light to dial in properly??

    HELP!!! This is driving me to the brink of insanity.

    Dan

    PS - If there is anyone in Los Angeles that might be able to help me directly, I would be very grateful. My final step is to send my setup to Quadrocopter so they can figure it out but would really like to reserve that as my last option.
     
  2. Steve Maller

    Steve Maller UAV Grief Counselor

    Joined:
    Oct 30, 2012
    Messages:
    3,979
    Likes Received:
    807
    I could swear that this guy was flying a T4i or something like that. The T2i is pretty old, and I'm not sure if the shutter and video system is up to the rigors of flying, but if you're getting results with the camera locked down, it's worth trying to tune the gimbal for it.

    https://vimeo.com/pgh7line
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,357
    Likes Received:
    1,161
    Dan:
    By how many percentage points are you changing to go between the chattering and rocking? Also, and apologies if you have already done this, but can you confirm the gimbal is balanced correctly, and the belts are tight?

    Thanks
    Andy
     
  4. Dan Coplan

    Dan Coplan Member

    Joined:
    Aug 8, 2012
    Messages:
    83
    Likes Received:
    1
    Andy,

    Yes, the gimbal is balanced correctly. Have done that a few times. And the belts are snug - not super tight, definitely not loose.

    I recently dropped tilt and roll gains from 120 to 70. At 120 chattering was bad but gimbal was keeping level. At 70 chattering was much better but there was still some chatter, but the gimbal was hardly keeping up so my video was rocking and rolling.

    Given this, there is no happy medium. If I drop the gains further to completely eliminate the chatter, the rocking and the rolling which is already bad, gets worse. If I up the gains to get the gimbal to keep up, the chatter gets worse.

    Dan
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,357
    Likes Received:
    1,161
    Hi Dan:
    I found that I ended up gradually narrowing the increments and decrements for adjusting the gains down to one or two percentage points. With large changes it was easy to overshoot the optimal values. It's very tedious to do this (wine or beer helps), but changes as large as 10% or even 5% up or down, made the search for the sweet spot really hard to find.

    Now that was just my experience -- for what it's worth.... :)

    Andy.
     
  6. Dan Coplan

    Dan Coplan Member

    Joined:
    Aug 8, 2012
    Messages:
    83
    Likes Received:
    1
    Andy,

    Good advice except that in my situation (and if I'm wrong, please let me know!) I seem to be on the wrong side of both sides of the fence. No matter which way I tweak the gains, I improve one issue while simultaneously worsening the other issue.

    Dan
     
  7. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Dan from a process of elimination:

    Have you tried swapping servos? Maybe a couple of servos that are worn out?
    Have you tried isolating which axis is problematic. Fly a sequence of Stabilization off, Tilt only, Roll only. Work on one axis at a time.

    I've been doing some tuning now that it is better weather. Currently at 145 Roll, 130 Tilt and running the Black O rings. 2 axis with Nikon D800/20mm about 1.3Kg. Getting very close with more testing today.
     
  8. Dan Coplan

    Dan Coplan Member

    Joined:
    Aug 8, 2012
    Messages:
    83
    Likes Received:
    1
    Gary,

    I haven't swapped servos but I did a thorough test in which I flew with Radians off, all on, just tilt, just roll, pan and roll only, roll and tilt only, etc. Test video is here...



    I edited out the pan tests as that doesn't seem to be relevant. You'll notice, aside from not the most stable flying (a bit windy that day), that the best chatter/vibration-free video is with the gimbal powered off. This eliminates issues with the copter and vibration isolators and camera setup - points directly to the Radians and/or servos.

    Begrudgingly, I'll be sending the gimbal in to Quadrocopter today because I simply can't think of anything else to try.

    Thanks everyone for your help, by the way!

    Dan
     
  9. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Dan

    Let us know if QC determines the solution.
     
  10. Tim Joy

    Tim Joy Active Member

    Joined:
    Aug 2, 2012
    Messages:
    405
    Likes Received:
    72
    My money is on the servos.
    I would also try using a light camera, like a GoPro, and I bet it will be very smooth.
     
  11. David Bone

    David Bone New Member

    Joined:
    Sep 30, 2012
    Messages:
    10
    Likes Received:
    1
    Hi Dan what's the verdict from QC?
     
  12. Dan Coplan

    Dan Coplan Member

    Joined:
    Aug 8, 2012
    Messages:
    83
    Likes Received:
    1
    The final verdict was essentially that my lens/camera combination was not a good setup. Radians checked out fine, servos checked out fine (they replaced them for me anyway), they said my balancing was pretty good, but they claimed to get similarly bad results. When they swapped my lens for a Canon 18-55 IS lens, they claimed the results were much better. The thing that gets me is that with the gimbal turned off, my video was pretty stable. It was only when I activated the gimbal that I had problems. This indicates to me that my lens/camera combination is just fine but I'll go ahead and get the recommended lens. If that solves my problems, fine. I just need to start shooting stable video!
     
  13. Scott Stemm

    Scott Stemm Member

    Joined:
    Apr 10, 2013
    Messages:
    140
    Likes Received:
    6
    Dan was your 24mm you were using the IS version?
     
  14. Dan Coplan

    Dan Coplan Member

    Joined:
    Aug 8, 2012
    Messages:
    83
    Likes Received:
    1
    No. It was a 24mm Nikon with Canon adapter to fit on to the T2i. Again - very stable with the gimbal stabilization off.
     
  15. Scott Stemm

    Scott Stemm Member

    Joined:
    Apr 10, 2013
    Messages:
    140
    Likes Received:
    6
    Thanks I was trying to find someone with the canon 24 IS as I am thinking of getting it and wondering how it was.
     
  16. Dan Coplan

    Dan Coplan Member

    Joined:
    Aug 8, 2012
    Messages:
    83
    Likes Received:
    1
    Gotcha. The nice thing about getting something like the 18-55 is that you're not locked in to a single focal length. And you could set up a separate servo to adjust your zoom setting while in the air. But I'm sure the 24 is sharper and lighter.
     
  17. Josh Lambeth

    Josh Lambeth Well-Known Member

    Joined:
    Jun 29, 2012
    Messages:
    1,313
    Likes Received:
    214
    Scott we are flying the 24mm IS and love it!

    Josh
     
  18. Scott Stemm

    Scott Stemm Member

    Joined:
    Apr 10, 2013
    Messages:
    140
    Likes Received:
    6
    Thanks Dan and josh
     
  19. Bill Ehman

    Bill Ehman New Member

    Joined:
    Feb 16, 2013
    Messages:
    11
    Likes Received:
    1
    Dan we have been test flying the Canon 18-55 IS on a Canon 60D. I know it is a cheap kit lens and the optics are not that of the 24mm IS, but we were having a hard time getting good, stabilized video with a non-IS lens (Tokina 11-16) so we gave it a try. The IS did help, and with a little post stabilization the video looks much better.

    Two things, we have been taping the zoom on that lens, as it will creep in flight if we don't. Also, if you get the 24mm IS and put it on your T2I, it will be the equivalent of using a 39mm lens because of the cameras crop factor.

    Now that we have managed to get some stable video (no wind of course) I am ready to upgrade my camera. Thinking either the 5D with the 24 IS or the GH3 with the 12-35 IS.

    Bill
     

Share This Page