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3A Arm -> Isoelastic?


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#1 Peter Schmehl

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Posted 22 January 2009 - 01:03 PM

Hey folks,

I`m thinking about converting to a G50 or G70. I`m currently owning a 3A Arm with Gold springs that supposedly holds up to 70 pounds... never had to load it to the max though. Can anyone tell me if this is the right weight capacity of the gold spring 3a arm?

According to my topic title, I`m asking you as well if there is a possibilty to get a 3a-arm isoelastic or close to it?

thanks for your help guys,

Pete
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#2 Eric Fletcher S.O.C.

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Posted 22 January 2009 - 01:08 PM

Hey folks,

I`m thinking about converting to a G50 or G70. I`m currently owning a 3A Arm with Gold springs that supposedly holds up to 70 pounds... never had to load it to the max though. Can anyone tell me if this is the right weight capacity of the gold spring 3a arm?

According to my topic title, I`m asking you as well if there is a possibilty to get a 3a-arm isoelastic or close to it?

thanks for your help guys,

Pete



70lbs is the gold spring capacity, not that I'd want to load it to that.

The 3A arm by design will never be isoelastic
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#3 Amando Crespo

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Posted 22 January 2009 - 09:26 PM

I can add, that only "Master series", "EDTv", and Provid (Tiffen´s) have or had isoelastics arms. Now, with G-50 and G-70 arms you can fit your isoelastic rank.
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#4 RonBaldwin

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Posted 23 January 2009 - 04:04 AM

just tried Mike O'Shea's G-70 and it is a nice arm. It's a bit lighter than my Pro arm with a bit more boom range. It can also be "detuned" to behave the same.
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#5 Jerry Holway

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Posted 23 January 2009 - 05:19 PM

The IIIa type arm (like the I, II, and III "3 spring" arms and all their descendants) are "iso-elastic" in their behavior at their maximum loads, but get progressively less iso-elastic as you lighten the load by relaxing the springs.

I.e., at the maximum load, they are relatively easy to boom all the way up or down (little effort) and unreactive (they don't fight hard to return to float point).

However, as the load is lightened, these types of arms require more effort to boom up or down, and they are more reactive (they fight harder to return to their float point).

Jerry

(I think the Gold Springs were supposed to be 65 pounds, regardless, I agree with Eric and would not want to carry that much all the time on one of those arms. I remember carrying 90 pounds!! once a long time ago (dumb), using extra bungees and then running....
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#6 Peter Schmehl

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Posted 22 November 2009 - 01:37 PM

The IIIa type arm (like the I, II, and III "3 spring" arms and all their descendants) are "iso-elastic" in their behavior at their maximum loads, but get progressively less iso-elastic as you lighten the load by relaxing the springs.

I.e., at the maximum load, they are relatively easy to boom all the way up or down (little effort) and unreactive (they don't fight hard to return to float point).

However, as the load is lightened, these types of arms require more effort to boom up or down, and they are more reactive (they fight harder to return to their float point).

Jerry

(I think the Gold Springs were supposed to be 65 pounds, regardless, I agree with Eric and would not want to carry that much all the time on one of those arms. I remember carrying 90 pounds!! once a long time ago (dumb), using extra bungees and then running....



Hey Jerry, sorry for not responding to your post for about 10 months. :)

thanks for you thoughts and help, I really appreciate it! I had a G70 for testing reasons yesterday from Christian Betz (Betz-Tools) and like I remembered from the prototype that we used in the 2005 workshop, it was quite nice!

I always had the feeling that my 3A arm really needs the load, it doesnt like to sit there with 35 pounds on top. So, what you were telling me about the 3A arm`s isoelasticity is absolutely what I was experiencing, but wasn`t able to pinpoint. :)
I talked to Dave Luckenbach and he wished a 3A arm for running shots, which is great I guess, since it is very stiff with the regular load.

Anyways, why were you carrying 90 pounds back in the days? And did it really help to add bungees? My maximum was a ARRI ST 35mm with approx. 57 pounds (camera weight), cuz they didnt have an ARRI 435 at that point, it was absolutely ridiculous. I got some pics as well. :)

hope everything is okay with you and maybe we`ll meet in amsterdam or in the US again.

Peter
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#7 Jerry Holway

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Posted 22 November 2009 - 02:14 PM

I talked to Dave Luckenbach and he wished a 3A arm for running shots, which is great I guess, since it is very stiff with the regular load.

Anyways, why were you carrying 90 pounds back in the days?

Peter

Peter,

One great thing about the G-50 and -70 (but not the -40) is that the iso-elastic response is user-adjustable; i.e., you can easily "tune" it to any response you want, from very iso to non-iso, regardless of the weight being carried. I happen to prefer very iso for all shooting, but that's just me and may not suit everyone all the time; hence the adjustment. The G-40 is fairly iso for all weights it carries (12-40 pounds payload), but can't be adjusted - one reason it's less expensive.

the 90 pound thing: I was caught on a low-budget feature in Canada and no lightweight anything from Panavision was available... and then I was running with it! Bungees did 1/2 the trick, the other was pure muscle... dumb but very stable shots!

Jerry
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#8 Peter Schmehl

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Posted 22 November 2009 - 03:20 PM

Hi Jerry,

thank you again, I liked the "ride control", very helpful! Especially if you need to hold the steadicam on a toplevel to get tall people eyelined. :) I didnt know that you got a G-40 by now, but I guess I would limit myself too much. I`d go with the G-70.

talk to you soon,

Peter



No comment on the genius non-Steadicam ARRI camera and mag. :)
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#9 Richard James Lewis

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Posted 22 November 2009 - 05:58 PM

Bridge plate, base plate, extension viewfinder... Clip on matte box tho, got to save the weight!

;)

R

Hi Jerry,

thank you again, I liked the "ride control", very helpful! Especially if you need to hold the steadicam on a toplevel to get tall people eyelined. :) I didnt know that you got a G-40 by now, but I guess I would limit myself too much. I`d go with the G-70.

talk to you soon,

Peter



No comment on the genius non-Steadicam ARRI camera and mag. :)


Edited by Richard J Lewis, 22 November 2009 - 06:03 PM.

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#10 RonBaldwin

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Posted 23 November 2009 - 08:52 AM

buddy...work smart not hard! Being vertical when you are an old man is a good thing!

Your assistant should be shot letting you (making you?) do that. You guys knew that extra 10 lbs of studio crap comes off right?

rb
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#11 Eric Fletcher S.O.C.

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Posted 23 November 2009 - 12:29 PM



No comment on the genius non-Steadicam ARRI camera and mag. :)


There is NO reason to fly a camera with the studio equipment on it. The Viewfinder strips off, so does the sliding baseplate.

Don't do it people, just say no.
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#12 Nikolay Kerezov

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Posted 23 November 2009 - 12:53 PM

There is a moment ,you should learn to say NO!


P.S.:Whats the story with the Plates ant the extention finder?
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#13 Brian Freesh

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Posted 23 November 2009 - 04:41 PM

Peter,

Looking at the photo, the plates look to be on there so that (overly long) rods can be used for the motors. Fair enough, but it seems perhaps you should get a dovetail for your rig that has rods, removable or otherwise for just such an occasion. I suppose it's safe to assume you didn't have 100% video optics to replace the studio optics with (and provide rods for the motors), but why is the extension viewfinder still on?

I'm also surprised that camera didn't come with a rear-load mag adapter (as opposed to the dual adapter it has on it) The rear-load adapter would have allowed the mag to hang vertically. There are also dual adapters that are 90 degrees, vs. the 45 degree on that camera.

I dunno the circumstances that led to this set-up, but hopefully you'll have more say in the matter next time!

Brian |-)~
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#14 Jess Haas SOC

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Posted 24 November 2009 - 02:47 AM

You think thats crazy look at this matte box!

~Jess

p.s. I swear there was a "good" reason for it, although we ended up removing it as it was scaring the actors!

Attached Files


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#15 Peter Schmehl

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Posted 25 November 2009 - 09:16 AM

Hey guys, thanks for being so caring about me. :)

I actually turned out fine and the shot as well. Although I will never be doing that again, it was ridiculously heavy and tough to balance.
The viewfinder had to stay on in order to counterbalance the canatrans and so on (dont quite remember) on the other side.
But I really do need a dovetail with built-in rods for sure, makes things alot easier, I guess.

They didn`t have any clue that they were going to need a steadicam to begin with, so I got a call to come over and make one shot only. I get there and they told me, that they don`t have a Arri 435 available and neither have a vertical mag to go with the ST at least.

Anyways, after all I didn`t think it was that hard to do, but certainly a "one timer"!!! Saying NO became my best friend since then. ;)

Take care guys,

Peter
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