Balancing a glidecam !?

[Mat Thompson]

Hi guys

I've just bought a Glidecam 4000 (main unit only at the moment). - I am trying to get this thing balanced out and I just can't achieve what I've seen others achieve in their balancing.

YouTube - Glidecam TEST!

If you watch this guy (from 25-35secs) he's throwing it from left to right/front back and the pillar stays vertical. I just can't seem to get my set-up like this !? In a stationary position its balanced and stands vertically but in motion things begin to sway. I've tried one more weight and one less weight at either end and the situation gets worse so I think I have the weight ok. Extension is about 8 inches. Camera is HD110.

Any pointers or advise much appreciated !?

[Amedeo Fabroni]

Hi Mat,
you have to move the gimbal on the post to achieve a 2-2.5 sec. drop time. If this is not possible you have to distribute the weights on the stage and on the bottom of the sled to achieve the correct drop time.
Amedeo

[Mat Thompson]

Hey Amedeo and many thanks for the swift reply.

The gimbal moves on the post ??? uhh....ok, how do I do this, it looks fixed to me !? 2 second drop time.....man this is way out then.

[Charles Papert]

The gimbal doesn't move on the post on the 4000. You have to alter the amount of bottom weight and/or monkey with the telescoping post to achieve the desired balance, i.e. drop time.

[Mat Thompson]

Hi Charles
Ahh ok...I didn't think it looked like it was meant to move. However that leaves me pretty stumped on how to get this drop time. At the moment it feels very camera heavy when it starts to sway BUT the drop is....well it certainly doesnt glide put it that way.

At the moment I have the weight in two piles and either end of the tray, tangent to the edges. 5 disks at each end !? Does this sound correct ?

Hhmmmm, puzzling

[Charles Papert]

OK, so your drop is....? don't leave us hanging!

To clarify: drop time is measured by swinging the rig to a horizontal position, letting go and counting how long it takes before the post swings back to a vertical position (it will obviously pendulum through that point repeatedly, but we only care about the first time). Make sure these are "real" seconds (one-missisippi!). If your drop is longer, remove weights; if shorter, add weights. Yes, with a standard setup you should keep the same number front and back.

If you find that the magic number is between weights, make it a little top heavy (which will result in a longer drop time), then extend the post a little bit and try again until you land at your desired drop.

[Mat Thompson]

Ok then....well i think about 1 second tops!


EDIT - RIGHT THEN !!! Now we are getting somewhere - Man this has taken some time. The key seems to be, get the drop time right first and then adjust the cameras position to achieve a better balance....or so it seems anyway!

I'd say the drop is just less than 2 seconds now....is this ok ?
It certainly seems better in motion, a lot more like the motion shown it that youtube link!

Another edit - HHmmm I'm not sure if it was just a flash in the pan or whether something has moved but its still swaying on my running test. Should these things really be that difficult to set up !?

[Danny O'Neill]

Hi Mat, I too struggled with my Glidecam, trying to balance it so i could throw it about. To get it like this you need a very low drop time, this means its neither top nor bottom heavy. however, truth is when using you wont actually be throwing it around like that, you will always have a hand on the post just below the gimble.

my optimal drop time is 3 to 4 secs drop time. remember were talking seconds, not count. so one one thousand, two one thousand and so on.

the reason the sled drops is because its everso slightly bottom heavy, whivh is fine because that is what makes it stable and your controlling hand can easily compensate. if it were very bottom heavy then it will have a short drop time and be harder to control.

[Mat Thompson]

Hi Danny
Yeah I'm starting to see that. BUT, I seem to have gone backwards and forwards. I've read some info that says you should set the post to minimum, some to max. Of course with the post shorter its going to need more mass and vice versa. However I seem to do it, the resulting action suffers from sway and the footage so far looks PISH !

I'm generally pretty good with stuff like this but its really driving me nuts. Can I ask what routine you would follow to balance this thing? oh and what cam your using?

[Charles Papert]

Mat:

The basic balance routine involves adjusting the camera platform side to side, front to back and top to bottom (bottom heaviness). Roughing in bottom heaviness first, proceed to rough in side to side and front to back. You will find that once you "fix" one axis, the next one that is the most obviously off kilter will manifest itself (i.e. if very front heavy, once you dial the camera back it may start to fall to one side, so fix that next).

Once you have static balance and you achieve a 2-3 second drop time, you can begin to work with your rig.

Understand that a rig will almost always "pendulum" or sway when you accelerate or decelerate. The video you posted must have had a fairly long drop time as little of this is apparent. A long drop time is tough to work with especially for beginners.

The true skill of operating a stabilizer is learning how to "contain" the forces of acceleration which is done with the hand on the post below the gimbal. That light fingertip touch that is required to aim the camera also is responsible for gently counter-acting the forces that are manifested on the rig during accelerations. It takes a lot of practice to achieve this--the rig does NOT do it for you. Expect to see plenty of sway and roll in your early efforts.

By the way--you ARE operating with both hands, yes?!

[Danny O'Neill]

I use an FX1 with high capacity battery and on my gc2000 i use all the weights so the post stays short (long post=more tilt inertia, which isnt normally good).

to balance i get my drop time roughly right, then do my side to side, front to back balance and fine tune my drop. fine tuning the static balance is then done by shifting the weights around.

the heavier the entire rig, the more stable it will beb but for this reason i got the vest as hand held killed me.

asyou adjust the weights and post you will find your balance will shift, just keep tweaking till its done. you may want a quick release as this gets boring after a while. its also worth a mention that the glidecam gimble is a little poo as you can balance it nicely then turn 90 degrees and its all out again.

[Tom Sherwood]

It took me forever to get mine balanced... I've only used it a couple times because its such a pain in the... gimbal.

[Charles Papert]

Good point about length of post, Danny. Shorter is always better in terms of overall operation (it helps equalize the feel between axes) but with a handheld stabilizer and a heavier camera, a longer post means less weight on the bottom which can make the rig less fatiguing to operate. Worth experimenting to find a happy medium.

And yes, the Glidecam gimbals are not that great when it comes to linearity.

[Mat Thompson]

Hi guys. OK today I've had a little more success. Charles thanks for your words, and I can see this thing isn't a plug and play solution for sure. I have got it balanced today, not perfect but enough to go out into a bit of local woodland and try it out.

I am going to capture some of the results shortly and I'll throw it up in this thread.

It is certainly hard on the wrist and I think a wrist brace would certainly help. I can also see that to use this for any length of time needs the vest/arm. Not only that though I did feel, 50% of my concentration was going into holding the thing up which of course means less on getting the shot right.

Anyway, for now thanks for all the help guys and I'll post some footage shortly....unless its terrible ;-) !

[Amedeo Fabroni]

Hi Mat,
I am glad you have improved your rig set up. Now it is time to fly. I am sure you'll have great satisfactions with your rig.
Best,
Amedeo