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Is it possible that internal camera parts are moving, throwing off balance? GH2 - Merlin


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#1 James Palanza II

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Posted 09 March 2012 - 11:48 AM

So, after about 3-4 hours I was able to pretty consistently get what I THINK is static balance. I also have about a 1.5 second drop time. My issue here is, when I move the rig left to right, suddenly the left and right balance is off. I can hear some slight movement inside the camera - do you think it could be throwing off the balance? If something is shifting left and right? My other issue is that, even though its balanced, I still incur some pendulum effect, even with my drop time, when I move it. I'm assuming this is just how it works and I need to learn to compensate.

Any insight into this?
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#2 William Demeritt

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Posted 09 March 2012 - 01:47 PM

1.5 second drop time, or any drop time really, will result in pendulum effect. Only completely neutral static balancing will reduce pendulum effect to nil. Even still, you may get some depending on the existing forces, such as a tilt down and a sudden push forward, because if the tilt down is still accelerating at the moment of the forward movement, the bottom sections acceleration backwards is increased, and turns into an upward force (pendulum up).

As far as parts moving, I think that cables shifting can be a culprit of small changes that result in big balance shifts.

What rig do you have?
What camera?
How is everything configured top and bottom?
Pictures of the setup?

If there are things rattling around inside the camera, it depends on the camera and the setup. Something as small as a tiny rock rattling around inside of a BL or ST might not make any difference, but the same rock inside of a Sony F3 on a Flyer might change it. More often, I find it's the cables improperly secured (not rubber-banded down, not velcroed in place, etc). Cables, even pigtails, may not weigh much, but they're often in unique positions that they are pretty far from the CG of the camera and the "pivot" of the sled. Torque = mass x distance from pivot.
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#3 Brian Freesh

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Posted 09 March 2012 - 02:17 PM

Will, It's a GH2 on the Merlin, cleverly hidden in the title.

As such, I doubt there are any cables to speak of, and wonder if the sound in the camera is the same as in prosumer Panasonic video cameras and some point and shoot cameras. If so, I've never noticed that have an affect on balance, though I've never tested it with a merlin.

Yeah, any steadicam is a pendulum, play around with drop times and practice, practice practice. Get the handbook, take the workshop, blah blah blah, it's been said a million times :)

I keep hearing about merlin's losing static balance and I always assume they mean it's doing a pendulum motion, but then they also mention the pendulum as a separate issue. So maybe there is something a little off or that most of us don't understand about merlins. Better to get a marlin.
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#4 James Palanza II

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Posted 09 March 2012 - 02:27 PM

Yes, its a merlin setup with a panasonic GH2 - I also have it on a manfrotto quick release plate. I'm going to give it another whirl here in a few hours and try to take a few pictures. I consider myself pretty hands on savvy, and I'm thinking something is amiss. I have it balanced left and right, forward and back, very well. But then I test the drop time, catch it and everything before it smacks anything, and lo and behold, it is no longer balanced. Its as if something is shifting mass.

1.5 second drop time, or any drop time really, will result in pendulum effect. Only completely neutral static balancing will reduce pendulum effect to nil. Even still, you may get some depending on the existing forces, such as a tilt down and a sudden push forward, because if the tilt down is still accelerating at the moment of the forward movement, the bottom sections acceleration backwards is increased, and turns into an upward force (pendulum up).

As far as parts moving, I think that cables shifting can be a culprit of small changes that result in big balance shifts.

What rig do you have?
What camera?
How is everything configured top and bottom?
Pictures of the setup?

If there are things rattling around inside the camera, it depends on the camera and the setup. Something as small as a tiny rock rattling around inside of a BL or ST might not make any difference, but the same rock inside of a Sony F3 on a Flyer might change it. More often, I find it's the cables improperly secured (not rubber-banded down, not velcroed in place, etc). Cables, even pigtails, may not weigh much, but they're often in unique positions that they are pretty far from the CG of the camera and the "pivot" of the sled. Torque = mass x distance from pivot.


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#5 William Demeritt

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Posted 09 March 2012 - 02:39 PM

Will, It's a GH2 on the Merlin, cleverly hidden in the title.


Your mother is cleverly hidden in the title.
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#6 Brian Freesh

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Posted 09 March 2012 - 02:45 PM

Your mother is cleverly hidden in the title.


Your face is cleverly hidden in the title.

James, call Derek at Tiffen, sounds like it might be a gimbal problem. Hopefully he can help you.
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#7 Alfeo Dixon SOC

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Posted 10 March 2012 - 10:43 AM

box it out boys... box it out!!!
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