Glidecam 4000 Pro Repaired at DVinfo.net

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Old May 16th, 2008, 06:34 PM   #1
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Glidecam 4000 Pro Repaired

Some of you may have been following my earlier threads about my Glidecam 4000 Pro's balance problems. I returned the 4000 Pro to Glidecam a little over a week ago. I mailed it from southern California via the postal service on Saturday, Glidecam Industries worked on it in Massachusetts on Monday, and mailed it back to me on Tuesday. An excellent turn around! Tom Howie personally took care of my 4000 Pro. He corresponded with me via emil prior to sending the unit back, arranged for the RMA, and personally re-aligned the gimbal and replaced the telescoping post section.

I received the rig back this Tuesday, but due to having to work for a living, couldn't do anything with it until last night. The gimbal seems perfectly aligned now. If I hold the Glidecam handle in my right hand and have good static balance, it remains in good balance when I swap the handle to my left hand, something it didn't do before!

I still have an issue with the rig swaying when I move forwards/backwards or laterally. The bottom of the rig gets "left behind" when I move, and sways when I stop. I asked Tom if there was anything I could do to the balance of the rig to solve that. His only suggestion was some subtle pressure on the central post, below the gimbal, to counteract the motion. I find that it really doesn't take much movement to get the rig swaying. Part of this may be that the camera's LCD screen could be acting as a sail or drag chute! Another thing Tom said, was adding weight and reducing the length of the central post, or conversely, removing weight and increasing the length of the central post are just systematic ways to adjust the balance of the vertical axis. It wouldn't help with my swaying issue.

I wonder, do the larger Steadicam rigs exhibit this problem too? Is it just part of the learning curve in using this kind of stabilization system?
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Old May 17th, 2008, 11:06 PM   #2
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Quote:
Originally Posted by Julian Frost View Post
I still have an issue with the rig swaying when I move forwards/backwards or laterally. The bottom of the rig gets "left behind" when I move, and sways when I stop. I asked Tom if there was anything I could do to the balance of the rig to solve that. His only suggestion was some subtle pressure on the central post, below the gimbal, to counteract the motion.
...
I wonder, do the larger Steadicam rigs exhibit this problem too? Is it just part of the learning curve in using this kind of stabilization system?
All stabilization systems have this to some extent, but the more bottom heavy the rig is, the worse this problem gets. If you think about it, it makes sense. Inertia is associated with weight. If there is a lot more weight on the bottom, then the bottom will want to stay behind when you move forward, or keep going when you stop. So one way to help with this is to make the rig less bottom heavy.

This is why we talk of "drop time". On a Steadicam Pilot or above, you can adjust the position of the gimbal on the sled post to make the rig more or less bottom heavy, then turn the sled post sideways (horizontal to the ground), then let go and count how long it takes to pass though vertical. The more bottom heavy, the shorter the drop time. A long drop time is 3 seconds or more. A short drop time is 2 seconds or less.

With a short drop time, you have the problem you describe, namely "an issue with the rig swaying when I move forwards/backwards or laterally". But this can be corrected. For example, as you start to move forward, reach down with the pinkie of you left hand and give it a subtle push at the back of the pole. This keeps the pole from swaying back when yo move forward. Similarly, when you stop, reach around with you middle and/or ring fingers and apply a little bit of pressure on the front of the post. For Steadicam operators that prefer short drop times, this technique is a must, otherwise you get the swaying described above.

Alternatively, you could go with a 3 second drop time, which will decease the swaying as you move. This also makes it easier to tilt. But with a lighter camera and stabilizer this makes it very easy to inadvertently tilt or roll the camera. Also, with a lighter rig outdoors, wind has more of an affect with with a longer drop time.

So drop time is a personal preference for each Steadicam operator, ranging from around 1.5 seconds to around 3 seconds.

Hope this helps.
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Old May 18th, 2008, 12:07 AM   #3
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Thanks for the reply, Dave.

Quote:
Originally Posted by Dave Gish View Post
If there is a lot more weight on the bottom, then the bottom will want to stay behind when you move forward, or keep going when you stop. So one way to help with this is to make the rig less bottom heavy.
With the Glidecam, you don't have much choice: You can't move the gimbal, so you must add weight to the base, or the rig will flip over!

Quote:
This is why we talk of "drop time" ...snip... A long drop time is 3 seconds or more. A short drop time is 2 seconds or less.
Mine is 3 seconds. Maybe I should try shortening it a bit and see how that affects it.

Quote:
With a short drop time, you have the problem you describe, namely "an issue with the rig swaying when I move forwards/backwards or laterally".
Well... I have a *long* drop time, and I get swaying, and it's really easy to tilt. To me, that makes sense... the longer the drop time, the more equally balanced the rig is both above and below the gimbal, so it would be easy to move. If you have a shorter drop time, then the rig is more bottom heavy, has more inertia, and is therefore harder to move. Is my thinking wrong?
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Old May 18th, 2008, 12:28 AM   #4
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The longer the drop time, the easier it is to tilt, and the rig will pendulum less. A shorter drop time means that the base of the sled has more mass, thus more inertia, and will be harder to get going, thus lagging behind the sled for a moment, or keeping going too far when stopping.

I'd stick with the drop time you have (though do feel free to try other drop times, it's a personal decision as Dave said), and just play with feathering out the starts and stops and keeping the pendulum action under control.
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Old May 18th, 2008, 12:39 AM   #5
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Ok, Tom, that all makes sense.

I've just taken the camera off the Glidecam, as I'm packing for my trip to England, leaving on Thursday morning. I have to work the next 4 days, so there's no time to play, unfortunately, and the Glidecam can't come with me.
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Old May 18th, 2008, 11:31 AM   #6
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Tom,
Have you heard anything from Peter, our instructor?
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Old May 18th, 2008, 12:26 PM   #7
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I've actually emailed him about something else, but no post-workshop email. I mentioned that I never got one in the email to him, maybe he'll send one out eventually.
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Old May 18th, 2008, 01:45 PM   #8
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These are all very good comments. Dave, yours is very thorough and well said.

Tery
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