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thoughts on reducing pendulum motion?


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#1 Herman Wong

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Posted 22 October 2013 - 02:17 AM

I'm flying with a Pilot and a DSLR.  I just wanted to gather some thoughts about trying to reduce pendulum swinging motion when the rig is perpendicular to me (e.g. panned 90degrees so I can circle around a subject).

 

With the LCD and battery now both perpendicular to my body, when I accelerate, the mass of these push the rig towards me.  I am using the 5-finger technique and my pinkie to attempt to push against the centerpost to counter that, but I feel that there is more pendulum motion than if the rig was in Missionary position.  Plus, even with the pinkie, it's difficult trying to keep the post 100% vertical.  I notice the pendulum motion more when the rig is perpendicular because my subject will appear slanted, whereas in Missionary position, pendulum motion would translate into slight tilting in video (which I guess is less noticeable).

 

At the moment the rig is set up with 2.5sec drop time.  Does it make sense to turn this into 3 secs?  My physics is a little rusty but I'm thinking that by moving the gimbal closer to the cg, the perpendicular force applied to the gimbal during acceleration would have less effect on the bottom part of the rig which (I hope) results in less pendulum motion.

 

So I'm not sure if my physics thinking is right or not. Does it make any sense? 

 

I understand it's a matter of preference but what are the benefits for people to consider a 2.5s over a 3s drop time? 


Edited by Herman Wong, 22 October 2013 - 02:18 AM.

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#2 Jerry Holway

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Posted 22 October 2013 - 07:47 AM

Your thinking on the physics is basically right, but your technique to prevent the pendular effects of moving and stopping the rig needs work and a bit more flexibility in thinking.

 

There is no single grip that does the work of aiming the rig, moving it about, and preventing pendular motion in all situations.

 

Have you taken a workshop?

 

These technique are some of the first things to learn and to practice.


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#3 Chris Van Campen

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Posted 22 October 2013 - 11:09 AM

There is no single grip that does the work of aiming the rig, moving it about, and preventing pendular motion in all situations.

 

 

Hi Jerry - is that video that you did where you filmed your gimbal hand positions still online? I went looking for it awhile ago and couldn't locate it.

 

Thought it was really cool to see the variety of grips you used, and maybe that would be helpful for Herman too. 


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#4 Jerry Holway

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Posted 22 October 2013 - 11:15 AM

Chris, I forgot about that.

 

I think it was part of the Steadicam Operators Handbook, on the focal website... but alas, I don't have time to do the search myself right now.

 

help from anyone?


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#5 Chris Van Campen

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Posted 22 October 2013 - 11:42 AM

Awesome, thanks Jerry!

 

links are here:

http://www.focalpres.../9780240823805/


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#6 Herman Wong

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Posted 22 October 2013 - 06:31 PM

Hi guys,

 

Thanks.  Yes I do understand that there are different grip positions required for accel and decel.  I think my problem is that by extending the pinkie and making it rigid to prevent the bottom from moving towards me, it tends to be in a position that either pushes the pole out too much or not enough to keep it vertical.  It's not bad if I walk slowly but as soon as I run/walk fast, the slanting become more prominent.


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#7 Jerry Holway

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Posted 22 October 2013 - 07:50 PM

If that grip doesn't work for you, find grips that do. It's not a big deal to keep a stick vertical; the trick is anticipating what you need to do and preventing it from happening. This is simply a matter of practice. Sp keep on practicing.


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#8 Herman Wong

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Posted 22 October 2013 - 09:56 PM

Ah hmm looks like I have not been doing it properly.  I should be using my thumb to counter the pedicular motion when the camera is in lateral position, and not my pinkie.

I'll have to work on this some more.

Thanks


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#9 Elliot Gabor

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Posted 30 October 2013 - 03:50 PM

Part of the issue is that the pilot is a relativley lightweight rig with little inertia.  The air resistance of moving quickly can push the rig off balance regardles of a slow drop time.  To compensate for this I recommend getting as close to the 10lbs weight capacity as possible and extending the post.  


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#10 Herman Wong

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Posted 16 November 2013 - 04:33 AM

Part of the issue is that the pilot is a relativley lightweight rig with little inertia.  The air resistance of moving quickly can push the rig off balance regardles of a slow drop time.  To compensate for this I recommend getting as close to the 10lbs weight capacity as possible and extending the post.  

 

Thanks Elliot,

that explains why I am having problems with this.  I'm probably only around 5lbs but I have extended the post to help with stability.


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#11 PeterAbraham

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Posted 16 November 2013 - 10:35 PM

If I may wade in here. Jerry's descriptive phrase, which I freely admit I've stolen to use when I teach, is that the pinkie ( or other fingers as needed ) are "preventers".

 

We live and die by Newton's Three Laws of Motion- and most notably his First Law:

" I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. "

 

Pretty useful to think about. Whether it's a Pilot or Ultra 2 or any other larger or smaller stabilizer, these rules apply- and it's always a bit pleasing to find out just how similar the feedback is that my fingertips get regardless of sled and camera size.

 

If I love a 3 second drop time, then the pendular effect felt by my fingertips and countered by my pinkie is the same regardless of rig and camera. Or to be more specific for those feeling an urge to be pedantic, my perception is that the force is the same on my fingertips. It may be slightly greater with a large sled and heavy camera.

 

But here's where I want to directly address what the OP'er of this thread said: We do not stop the pendular effect produced when you start moving by pushing back against the post with the same force. That indeed would make the centerpost sway in the OTHER direction, producing displeasing results.

 

Instead, learn to find the 180º spot around the post from the direction the middle of the lens is pointed. Using whatever finger makes sense ( usually a lower finger on the post ), prevent the post from swinging when you initiate motion by starting to walk. If you think about your finger placement on the post relative to the lens, you'll realize that shooting Don Juan opposed to Missionary opposed to shooting 90º to the direction you are walking will result in different fingers being used.

 

This is articulated fully in the book that Jerry and Laurie wrote. But fair to say- one does NOT push back hard by way of stopping a certain pendular motion- that would create an opposite swing. Instead, we stop the pendular motion with a fingertip without overcompensating. This takes a lot of practice. Don't be frustrated if you under-do it or over-do it for a while. It's one of the complex but core skills required.

 

Hope this helps !

 

Best to all,

 

Peter Abraham, S.O.C.


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#12 PeterAbraham

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Posted 16 November 2013 - 10:39 PM

 

Part of the issue is that the pilot is a relativley lightweight rig with little inertia.  The air resistance of moving quickly can push the rig off balance regardles of a slow drop time.  To compensate for this I recommend getting as close to the 10lbs weight capacity as possible and extending the post.  

 

Thanks Elliot,

that explains why I am having problems with this.  I'm probably only around 5lbs but I have extended the post to help with stability.

 

 

Hi Herman,

Send me a PM, I will be glad to help you out more with this.

Best

Peter


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