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Steadicam Pilot Iso-Elastic? Really?


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#1 Benjamin Freedman

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Posted 19 May 2009 - 10:10 AM

Howdy...

I have an EX-1 flying on a Steadicam Pilot. I have read that this arm is supposed to be 'iso-elastic', which I've read means that it stays where you put in vertically in space.

Well, I have the arm trimmed so that the weight of the sled keeps the arms basically horizontal when hands-off. Right in the middle of their range.

I would assume that if I raise or lower the arm, it is supposed to stay basically where I leave it, but I find that if I raise it, it wants to lower back down to center, and if I lower it, it wants to raise back up. To keep it in either an upper or lower position requires constant effort on my part.

Can anyone tell me what I'm doing wrong?

Thanks.

-Ben
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#2 Brian Freesh

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Posted 19 May 2009 - 10:44 AM

Hey Ben,

Don't fret, you're doing everything exactly correct! Isoelastic actually describes how much the arm wants to return to the balance point. An isoelastic arm doesn't try as hard, meaning if you need to boom up or down, you don't have to use much force to do it. An arm that is not isoelastic will take more force, causing the operator to work harder. You don't want an arm that will not seek a specific point, wouldn't make a very good shock absorber!


Brian |-)~
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#3 Benjamin Freedman

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Posted 19 May 2009 - 02:24 PM

Hey Ben,

Don't fret, you're doing everything exactly correct! Isoelastic actually describes how much the arm wants to return to the balance point. An isoelastic arm doesn't try as hard, meaning if you need to boom up or down, you don't have to use much force to do it. An arm that is not isoelastic will take more force, causing the operator to work harder. You don't want an arm that will not seek a specific point, wouldn't make a very good shock absorber!


Brian |-)~


I don't understand, Brian... Why would you want the Steadicam to seek a particular boom height? Why not just maintain it where it is, and isolate the body movement....

The Tiffen Website clearly states for the Pilot:

The Iso-Elastic™ arm is a two-section, articulated, design that can be adjusted while supporting the camera. With this patented, unique design, the Steadicam operator can smoothly and effortlessly raise or lower the arm throughout its 28 inch boom range. The iso-elastic arm is also non-reactive – improving vertical stability and control in all operating conditions, from lock-offs to fast running shots over rough terrain.

... and then lists as features:

Frictionless, Silky-Smooth Iso-Elastic Performance

I understand some of the bigger Steadicam rigs are truley 'isoelastic', in that they'll stay basically at the height you put them. Can anyone comment on this? And why Tiffen would mislead if the Pilot is not truley IsoElastic?

Thanks

Ben
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#4 Brian Freesh

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Posted 19 May 2009 - 02:55 PM

Hey Ben,

That quote from Tiffen's website says nothing about the arm staying where you put it, it tells you the same thing that I said, that the arm moves "effortlessly" due to it's iso-elasticity. While I'm no expert, i would concede that probably a truly 100% iso-elastic arm would stay exactly at the level you leave it. But again, that's not what you want. Because it would only stay at that level relative to you. If you step up, the arm as a whole would move up and so would the lens. You'd have to constantly compensate with your own arm booming opposite to your steps. Doable in basic situations, but certainly not preferable. It's the same thing with the pendulum effect of the sled. You can balance it so that it stays at whatever angle you leave it, but why would you? To be fair, there are applications for that, but I'm talking about general operating circumstances.

Larger Tiffen arms operate like your Pilot's arm, though some of them have adjustable iso-elasticity. Tiffen has not misled you. A non iso-elastic arm simply takes more force to push all the way down or pull all the way up, because the arm more strongly wishes to remain at the balanced level.

Fly safe, enjoy your pilot!

Brian |-)
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#5 Chris McKissick

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Posted 19 May 2009 - 03:18 PM

The arm stays where you put it as long as you keep your arm hand at that positon. It takes practically no force to keep it there.. Not like other non-iso-elastic arms do.
Non iso-elastic arms have a strong tendancy to want to move back to the center, which means you have to really pull or push hard, to boom up or down and keep it there...

If you get your hands on a g50 or g70 arm, you can check out the feeling by removing the iso-elasticity with the ride knob.

But i'm just basically repeating what the other guys already told you :o)
Relax, you got a great rig!

Cheers,
Chris
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#6 Brian Freesh

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Posted 20 May 2009 - 12:33 AM

Ha, Chris, good point, it's not like you're gonna let go of the gimbal anyway! If it takes so little force to hold up, or down, then the effect you're looking for is essentially present.
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#7 Kevin Andrews SOC

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Posted 26 May 2009 - 06:59 PM

Sounds defective, you should sell it to me for half off. ;)
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#8 Andrey Yazydzhi

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Posted 17 June 2009 - 12:18 AM

Sounds defective, you should sell it to me for half off. ;)

Ben
Iso-Elastic means the smalest force difference between the down and up positions
Zero-graviti means zero difference (comfortable but do not absorb shaking)
The oldest arms had about 16 kilos difference

Best,
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#9 Eric Fletcher S.O.C.

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Posted 17 June 2009 - 01:04 AM

The oldest arms had about 16 kilos difference



Ummm no. The old Model 1, 2 and 3 arm's required a 6lbs difference from midpoint to either top or bottom, not 35.2739619 pounds

The current Pro arm BTW needs 2lbs in either direction
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