Dynamic Balance

[Dan Coplan]

Ok, I'll read it again and try to wrap my head around it a bit better. Thanks to everyone for clarifying.

 

Dan "Oh Well" Coplan

[Alec Jarnagin SOC]

Dan,

 

As you get to know your sled, you'll have a good idea of where things should be pre-set for any given configuration allowing you to achieve dynamic balance quickly without prolonged math.

 

Check out: http://www.steadicamforum.com/forums/index...ic=2562&hl=

 

Cheers.

[Dan Coplan]

Alec - thanks for pointing out that link. I didn't look deep enough into the archives to see it.

 

Dan

[Peter Abraham]

Dan,

 

As you get to know your sled, you'll have a good idea of where things should be pre-set for any given configuration allowing you to achieve dynamic balance quickly without prolonged math.

 

I couldn't agree more. Many of us have struggled for years to get to know our sleds to the point where we can effortlessly communicate with them on a daily basis. God knows I tried all the old tricks and read all of the best books on the subject- Zen And The Art of Steadicam Maintenance, Five Steadicam Shots You Will Do In Heaven, The Seven Sled Tricks of Highly Successful Operators. I finally found the path by reading a slim little volume by Herman Hesse. It's called Sleddartha, and I highly recommend it. Only through careful effort can you truly get to know your sled.

 

If the high road approaches fail, woo it with teflon lube and a fresh set of gimbal bearings. Some sleds are queens, some are whores. Know your sled. :D

 

Peter " My Sled Left Me For A Muscular Handsome Man From Philly " Abraham

New York

 

p.s. He's right. Re-read the primer, and don't get ruffled that it doesn't make sense. It DOESN'T upon first blush, but the physics and applications are sound, and will work no matter what rig you own. Contrary to some vicious rumors, one can dynamically balance a Flyer. I did it two weeks ago at a workshop in NYC. Assuming you can X-Y at the top, you can balance the thing up. I never tried but suspect it woulda been a bitch to dynamically balance my Model I with only an X top stage, and a side to side shifting battery down below........

[mark morgan]

Dan,

 

As you get to know your sled, you'll have a good idea of where things should be pre-set for any given configuration allowing you to achieve dynamic balance quickly without prolonged math.

 

I couldn't agree more. Many of us have struggled for years to get to know our sleds to the point where we can effortlessly communicate with them on a daily basis. God knows I tried all the old tricks and read all of the best books on the subject- Zen And The Art of Steadicam Maintenance, Five Steadicam Shots You Will Do In Heaven, The Seven Sled Tricks of Highly Successful Operators. I finally found the path by reading a slim little volume by Herman Hesse. It's called Sleddartha, and I highly recommend it. Only through careful effort can you truly get to know your sled.

 

If the high road approaches fail, woo it with teflon lube and a fresh set of gimbal bearings. Some sleds are queens, some are whores. Know your sled. :D

 

Peter " My Sled Left Me For A Muscular Handsome Man From Philly " Abraham

New York

 

p.s. He's right. Re-read the primer, and don't get ruffled that it doesn't make sense. It DOESN'T upon first blush, but the physics and applications are sound, and will work no matter what rig you own. Contrary to some vicious rumors, one can dynamically balance a Flyer. I did it two weeks ago at a workshop in NYC. Assuming you can X-Y at the top, you can balance the thing up. I never tried but suspect it woulda been a bitch to dynamically balance my Model I with only an X top stage, and a side to side shifting battery down below........

looked on amazon could'nt find the book,sleddartha could you please point mre in the right direction,i love knowledge,even that i don't have a problem with my DB. mahalo for dakine help if can

[Peter Abraham]

--choking-- I think I've been whooshed !!!

 

It was a pun and no more. The only primer is Jerry Holway's Primer and at this point it is really required reading in our field. :)

 

Peter

[jay kilroy]

Peter " My Sled Left Me For A Muscular Handsome Man From Philly " Abraham

New York

 

Alan is not that handsome, kind of, but not really. :P

[Chris Haarhoff]

Without getting too far into other peoples ricebowl, Dan's original post reminded me of how, with a few weeks to burn many years ago, we got to understand some of the nuances of dynamic balance. With access to a machine shop we machined a perfect cylinder of steel to represent the weight of the camera. This was about three inches high and about five inches in diameter. We removed the top stage and screwed the cylinder directly into the post, hence creating a perfectly balanced and centralised mass over the post. What we were hoping for was to test the flat spin of the sled with various configurations of the sled ( recorder on/off, placement of Seitz receiver, monitor hood, video xmtr etc. ), and exterpolate these findings to the various camera configurations.

In a sense, we were trying to find consistant correlations to arrive at some kind of a unified theory. I kid you not, we spent three weeks doing this, tabulating all our results. The patterns that we were looking for existed only with a given mass, be it our perfect weight or the camera lens configurations, and were not exportable from one camera to the other.The most glaring result of this in my opinion was that as much as we wanted to regard the actual camera as a benign participant, treating our sled as the controllable variable....we could not. I know I differ with Garrett, Jerry and about a thousand others, but I feel that to be truly in dynamic balance you have to spin each configuration of camera on the day. There are no short cuts, handy formulas or quick rules of thumb that will get you anywhere as close as the real deal. Balancing the sled up on it's own is nuts as it does not take into account the odd distribution of masses within the camera itself. Whether dynamic balance is truly necessary is a debate on it's own, and although I live and die by it, I can cite a couple of the finest operators that think it's just a pile of dingo's kidneys.

[Jerry Holway]

Chris-

 

I remember discussing your dynamic balancing efforts with you way back when. Now it seems totally clear that your centralized mass was the start of the confusion....

 

What the math in the primer (based on Arnold DiGuilio's original formulas) tells you will get you really close to dynamic balance, and it tells you what do do if you change things, what's improtant, what's not... it even explains all of the "oddness" you discovered way back when. We just didn't understand all what the math was telling us, way back then.

 

As you suggest, spin balancing is the only way to actually achieve dyanmic balance. We can't measure and weigh every component precisely, but typically we can get very very close with the math and then tweak in the real world. I never do the math on set because it's so damn easy to spin balance, and doing the math has told us all where to start our balancing. So we are always close, and a few spins later we are there.

 

As for the donkey's parts, dynamic balance simply means that if you pan the rig, it will pan flat at any speed. If you are not in dynamic balance, it won't. The sled will tilt up or down or roll or wobble, more or less, and you must do something to correct it. You must intercede, more or less.

 

In our early days of our ignorance, we all made the corrections, and we did it damn well, blissfully. But we all worked a lot harder than we needed to, and our operating was not as good as it might have been.

 

So great operating can be done without it, and the great majority of what makes great operating has absolutely nothing to do with flat pans.

 

But to the extent that you want the Steadicam to help you get a particular kind of shot - in this case a nice flat pan - then dynamic balance is important. To the extent that you want the precision bearings in the gimbal (for which we all paid a small fortune!), to help you get the nicest, flatest, and infintely smoothest pan, then you should be in dynamic balance. When that doesn't matter, then dynamic balance can be ignored (and you don't need the bearings, either, you're manhandling the rig anyway).

 

Why you suggest that dynamic balance doesn't matter for some folks - or that maybe it shouldn't matter - confuses me immensely. Ignoring dynamic balance certainly will not make it easier for new operators. Handicapped, they will have to learn all those old tricks which, frankly, you and I both know, don't work quite as well.

 

Jerry

[Chris Haarhoff]

Hi Jerry

 

I agree with you wholeheartedly regarding the importance of dynamic against the backdrop of over two decades of trying to reach a kind of unified theory. I've just never been able to agree with the idea that the variable mass of the camera need not be considered and that the rig itself can be built in dynamic balance. The original Master Series was considered to be in true "dynamic balance" regardless of the camera it carried, and I've heard this concept repeated over the years.To me the in a spin/pan situation the forces that apply leave the camera/rig with no innate understanding of which is up and which is down. In the mind of the Steadicam the Camera may just as well be the sled and visa versa so to consider one without the other is all that I disagree with.....I may still be wrong, so feel free to convince me otherwise.

[Jerry Holway]

Chris,

 

I think we are on the same page. The sled by itself isn't in dynamic balance; it always is the sled with the camera and everything attached that must spin flat.

 

One idea behind the master series - that was abandoned for a lot of reasons before it was introduced- was that the sled (with camera) could stay in dynamic balance as one moved the monitor around... it's theoretically possible to do all that with sensors and motors and all that, but a simple mechanical means wasn't going to do it and it weighed too much and could not account for anything else one might add to the base or the changing length of the sled as one telescoped the post.

 

I wrote the primer to try to comprehensively clarify all this, both with the math and practically, because a lot of nonsense was being put forth, misconceptions were running rampant, etc., BTW, I learned a lot and discovered some curious things in doing so.

 

thunderstorms booming all around, must sign off.

 

Jerry

[Michael Binder]

Hello,

 

my problem is, that i can not get in dynamic balance (not in static balance too) with my rig (an artemis efp), although i can adjust the battery. Maybee you can help me:

 

The trouble starts when i try to hold the rig in static balance. When i tilt the camera looking down (in front) for expample to make the dop-down-time-test, the camera wont get back, so it is strait hanging down. It stays a little looking down. When i do otherwise, the camera tilt looking up, it doesnt stay straight hanging down again, it stays a little bit looking up.

 

Same thing with tilting left or right (for dynamic balance). Now the righ stays hanging litle left or right, depending on which side i make the tilt.

 

My drop down time is usualy for working about 5 seconds or more. but i tried this also with a drop down time of 1 second. I tried it with different cameras AND mounting plates (Sony and Ikegami).

 

My explanation at first would have been that the problem is the camera. But in all 4 directions? I took notice of this just a few weeks ago.

 

Has anyone an idea for me?

 

Thanks a lot

 

Michael

[mark morgan]

hey michael, i have an artemis rig as well, and i can acheive DB in a matter of minutes,i start by finding the CG of the camera and then i place the wedge plate a little off dead center on the post,now i try for a drop time of about 2 to 3 seconds,1st lowering the bottom section and if need be raising or lowering the gimble,now i put the rig horizontil and turn it to its side where the lens is say pointing at the wall,then i let the rig drop seeing if the rig falls more towards the battery side or the monitor side and then adjust accordingly,that gives me an idea of where my DB is at,also look into the jerry halloway primer balance techniques on the forum here or on the tiffen website,and like myself go for the workshop l

Hello,

 

my problem is, that i can not get in dynamic balance (not in static balance too) with my rig (an artemis efp), although i can adjust the battery. Maybee you can help me:

 

The trouble starts when i try to hold the rig in static balance. When i tilt the camera looking down (in front) for expample to make the dop-down-time-test, the camera wont get back, so it is strait hanging down. It stays a little looking down. When i do otherwise, the camera tilt looking up, it doesnt stay straight hanging down again, it stays a little bit looking up.

 

Same thing with tilting left or right (for dynamic balance). Now the righ stays hanging litle left or right, depending on which side i make the tilt.

 

My drop down time is usualy for working about 5 seconds or more. but i tried this also with a drop down time of 1 second. I tried it with different cameras AND mounting plates (Sony and Ikegami).

 

My explanation at first would have been that the problem is the camera. But in all 4 directions? I took notice of this just a few weeks ago.

 

Has anyone an idea for me?

 

Thanks a lot

 

Michael

[Michael Binder]

Hello Mark,

 

thanks for your answer. First at i all i want to say, i have allready been on an workshop :) (Munich, at sachtler with Curt Schaller)

 

So the problem is not, that i would not know how to do it (i hope so :ph34r: )

 

But this is not only the only problem. There would be for me just one chance: stay always in horizon? so if i make a diagonally picture, the camera wont come back to horzion. as i told, if i tilt the camera about 45 degrees left side, the camera stays about 5 degrees left. so i have to tilt her a little right, that it comes back to horzion.

 

Same if i take camera a little up to shoulder for rest. tilting it up, wont let come her back straight hanging down. that is the real problem. i would have always to "rebalance".

 

lg michael

 

PS: another question btw. how do you guys (in reals world, without calculating) balance the rig, with having a focus-receiver and motor on the rig. i can not ad this things to camera for finding cg. So just by "feeling" and experience?

[Alec Jarnagin SOC]

Michael,

 

If I understand you correctly (I just worked a long day and there may be translation issues), you are saying that you have balanced the rig, but after tilting in any given direction, the rig does not return upright as it should, rather it returns to a slightly canted position close to its previously balanced point?

 

If this is the case, make sure nothing is shifting while you tilt (monitor moving, camera plate slipping, etc). If all this is okay, see if you can get your hands on another gimbal and test it out. Also, if you have any quick releases on the rig (rings that allow you to take the rig apart quickly - i.e. separate the top stage from the center post) make sure they are tight with no play.

 

If need be, get an identical rig and keep swapping pieces, one at a time, until you find the culprit. (Do this with a steel practice cage or a very solid camera so you can safely eliminate parts on the camera moving - i.e. a bad camera quick release plate, battery, etc). While you do these tests listen for noises and also try gently placing fingers on the center post to see if you can feel vibration.

 

Good luck.