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2013 New rigs - Real World Improvements?


John E Fry

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The reason we, as Steadicam operators, became interested in dynamic balance was because the monitors in the Model II and III were raised up from the base for better viewing, The masses of the monitor and battery and base were no longer coplanar as they were in the Model I, and the result were rigs that generally did not pan flat.

 

The model one behaved very nicely in pans, and was pretty much dynamically balanced when it was balanced statically, because all those masses were coplanar.

 

If your monitor and batteries are coplanar (the c.g.'s are on the same plane), as they are in some rigs, extending the post will not affect dynamic balance.

 

However, if your monitor is raised from the battery (as it was for better viewing in those and some other models, Including the PRO), one has to work at little harder to achieve dynamic balance.

 

And, if your monitor c.g. is raised up from the battery c.g. (i.e., not coplanar) for viewing or balancing, then changing the length of the sled will have an effect on dynamic balance.

 

How much of an effect depends on how much the monitor c.g. is raised from the battery c.g. Raising the monitor up more - as a percentage of the total length from the battery c.g. to the camera c.g. - will create more of a difference.

 

It's why the model II and III was typically so out of dynamic balance when dynamic balance was not considered - the monitors were raised quite a lot towards the camera.

 

In practice, in the field, all that one needs to do to achieve and maintain dynamic balance is pretty straightforward, even if your monitor c.g. is quite far up from the battery.

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Interesting to see that you didn't extend your post, Robert, as I think that would have given you a few inches to move the gimbal down/camera up, and it would have given the Op a much better angle to view the monitor from.

 

I've always had a thing for built-in superposts, but I have yet to encounter a circumstance where an extremely low or high angle is called for spontaneously. Okay, I lie, a lot of directors want the camera "in the weeds". Being just under 6', I throw the longest arm post in the d-bracket and I'm within 2" of scraping with the arm all the way down. Definitely not an optimal way to Op, though.

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Hey Twojay!

 

It was really just an off the cuff "hey let's try this" test and a workshop. We lost so much time configuring the Ultra2 none of us were interested in playing around with it from there. Movin' on!

 

Hopefully Evrim will post his videos soon plus I'll be in LA next week and would be happy to document a more controlled side by side.

 

Robert

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The reason we, as Steadicam operators, became interested in dynamic balance was because the monitors in the Model II and III were raised up from the base for better viewing, The masses of the monitor and battery and base were no longer coplanar as they were in the Model I, and the result were rigs that generally did not pan flat.

 

The model one behaved very nicely in pans, and was pretty much dynamically balanced when it was balanced statically, because all those masses were coplanar.

 

If your monitor and batteries are coplanar (the c.g.'s are on the same plane), as they are in some rigs, extending the post will not affect dynamic balance.

 

However, if your monitor is raised from the battery (as it was for better viewing in those and some other models, Including the PRO), one has to work at little harder to achieve dynamic balance.

 

And, if your monitor c.g. is raised up from the battery c.g. (i.e., not coplanar) for viewing or balancing, then changing the length of the sled will have an effect on dynamic balance.

 

How much of an effect depends on how much the monitor c.g. is raised from the battery c.g. Raising the monitor up more - as a percentage of the total length from the battery c.g. to the camera c.g. - will create more of a difference.

 

It's why the model II and III was typically so out of dynamic balance when dynamic balance was not considered - the monitors were raised quite a lot towards the camera.

 

In practice, in the field, all that one needs to do to achieve and maintain dynamic balance is pretty straightforward, even if your monitor c.g. is quite far up from the battery.

Jerry,

 

Great explanation. As relates to a system such as the XCS or PRO, with a two-stage post system: If the monitor is left exactly where it was when the post was fully collapsed, would the sled still be in dynamic balance, even though the chances are that you'll have raised the camera's c.g. away from the gimbal to obtain a similar drop-time as you had when the post was fully collapsed?

 

This seems to be what Jens has alluded to and it's a bit confusing for me to wrap my head around why the DB would be lost by simply moving the corresponding weights away from each other on the y-axis.

 

Thanks for any insight you can give.

 

EDIT: did not notice this thread had grown so much and other similar questions have been asked. My bad for the clutter!

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Twojay-

 

Gimbal position is not relevant to DB, although a very bottom heavy rig can mask the imprecision of less than perfect dynamic balance, or moving the gimbal might make it spin flat but upside down.

 

If the c.g.s of the batts and monitor are coplanar, then the c.g. of the camera is going to be in line with the centerline of the post system. Changing the length won't have any effect on DB. You can think of that setup as two flywheels on a shaft (one flywheel is the batt and monjitor, the other is the camera).

 

Assume your monitor c.g. is raised up when you first get into dynamic balance. As the post system is extended or compressed, that monitor will be raised up to a different percentage of the total length (batt c.g. to camera c.g.). The more the monitor is raised from the battery, the more its height will change percentage wise, and the more you will have to move components (usually the battery and the camera) to get the rig back into dynamic balance.

 

With your own rig and your usual set up, you tend to get a feel for this rather quickly - and again, making some marks on your rig with a practice camera at home will help when time is short on the set.

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Twojay-

 

Gimbal position is not relevant to DB, although a very bottom heavy rig can mask the imprecision of less than perfect dynamic balance, or moving the gimbal might make it spin flat but upside down.

 

If the c.g.s of the batts and monitor are coplanar, then the c.g. of the camera is going to be in line with the centerline of the post system. Changing the length won't have any effect on DB. You can think of that setup as two flywheels on a shaft (one flywheel is the batt and monjitor, the other is the camera).

 

Assume your monitor c.g. is raised up when you first get into dynamic balance. As the post system is extended or compressed, that monitor will be raised up to a different percentage of the total length (batt c.g. to camera c.g.). The more the monitor is raised from the battery, the more its height will change percentage wise, and the more you will have to move components (usually the battery and the camera) to get the rig back into dynamic balance.

 

With your own rig and your usual set up, you tend to get a feel for this rather quickly - and again, making some marks on your rig with a practice camera at home will help when time is short on the set.

 

Copy all of that, Jerry.

 

I believe you may have answered my question, although indirectly. An example for folks to keep in mind as I work through this: I run a PRO III rig with an XCS TB-6 monitor with the bottom of the monitor being able to sit flat against the ground, along with the two bottom batteries (some may call this coplanar; I just call it awesome).

 

Now, I also use anywhere from a 4 to 5 second drop time... Sometimes I run absolutely neutral. With that in mind, I *ALWAYS* have my rig in DB if I set my battery hanger out to 2.5 (PRO GEN III Batt Hanger owners know what I'm referring to; For those that don't, that is a pre-marked scale which shows you how far out you have slid you rear battery/batteries). This DB has been verified via both the spin method and the Eric Fletcher "sideways drop method" and both M.O.'s yield the same rear-battery/batteries-to-monitor-relationship.

 

As an aside, I -- up until now -- have never repositioned my monitor from its "flat" position for reasons of always maintaining my DB. This thread has made me question this choice.

 

Given the above, if I release the upper-to-lower-post-clamp and extend both sections all the way out *WITHOUT REPOSITIONING MY MONITOR OR REAR BATTERY/BATTERIES* I should still be in DB, despite having to reposition my gimbal lower on the upper post section (effectively raising the lens height from the floor I stand on, relative to the lens-to-floor-height before extending the post sections) to obtain an identical drop-time to the fully-collapsed rig with the same camera/above the gimbal mass(es).

 

Yes? Because that to me makes sense. And having the rig lose DB because of a simple change in gimbal height does not.

 

As an example, let's say we take two PRO rigs which are both of the same build and both fully collapsed. DB is obtained (in this example) by keeping the monitor flat and the rear battery/batteries at the 2.5 mark.

 

Rig # 1 has an Alexa with a Pana G-Series Primo, LMB-5 and one ND and one CLEAR in the stages. 2 Preston DM2's, a BOXX transmitter and an Anton Bauer Dionic HC behind that (yes, a metric sh*t-ton of pan-inertia -- just how I like it).

 

Rig # 2 has an EPIC with a 135mm Super Speed MKII, one Preston DM2, a BOLT Transmitter, a RED ONE Cradle with a RED BRICK attached to power camera.

 

For simplicity's sake (and completely innacurate as regards the accuracy of the actual camera-build weights about to be given): The camera setup being placed onto the PRO rig in Rig # 1 weighs 40lbs. The camera setup being placed onto the PRO rig in Rig # 2 weighs 30lbs. The point here is camera setup paced onto Rig # 2 is 10 lbs less than the one being placed onto Rig # 1.

 

Obviously, if both rigs are kept fully collapsed and an identical drop-time (say of 4 seconds) is desired of both rigs, Rig # 2's gimbal will be lower on the upper post, than Rig # 1's, directly attributable to the lower above-the-gimbal weight.

 

Using this as an example, why are both rigs, identical except for the weight of camera setups, and the consequent positions of their gimbal relative to the top-stage/upper-j-box, etc.) in DB? Yes, I posit this as an absolute as I have field-tested this very same example and both cameras are in DB with the rear battery/batteries set to 2.5. Yet, when we talk about extending the post, all things remaining constant except the vertical disparity between the two masses, some Ops believe DB will be lost. THAT makes no sense to me. I've been wrong before and I am making no claim to being correct in this case.

 

If a difference from camera to camera, weight-wise, makes DB change, then sure, a lengthening of the post would also change DB (as these both result in a change of gimbal height relative to top-stage). However, I believe we all are in agreement that above the gimbal masses and distribution thereof will not affect DB should the below the gimbal masses retain their relationship. Ergo, camera weights -- or a weight disparity between two above-the-gimbal setups -- and the consequential difference in gimbal height on the upper post (still using the same PRO rig as an example) should not change DB.

 

All a lengthening of the post/y-axis should do is make the rig have even greater pan inertia from the greater spread of masses. In layman's terms (mine): the rig is slower.

 

It's 4:16am PST. It's bed-time for me.

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I may be wrong here, so please correct me if I am.

 

My understanding is that lengthening a normal post, if the batteries and monitor stay in constant relation to one another, as you say, will not lose DB.

However, these post movements often come with keeping the monitor in vertical relationship to the topstage for the sake of viewing position, with the batteries being lower, sometimes significantly. This is especially true with superposts.

 

Just a thought

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Alex-

 

Keeping the relationship of the batts to monitor will maintain dynamic balance when extending the posts only if the batts and monitor are coplanar.

 

If the monitor is raised from the battery, then changing the length of the sled will change the DB.

 

Gimbal position is irrelevant, by definition, so moving only the gimbal will not change dynamic balance.

 

However, a very bottom heavy rig can mask the wobble of a rig that is slightly out of dynamic balance.

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Guys, you are over-complicating things.

 

If you fly the rig with the monitor on the same level as the batteries (Coplanar) and you have that mass balanced both for aft and side to side, no matter what you put on the topstage, how long you make the post or how you set drop time you will NEVER be out of dynamic balance.

 

It's that simple. No Math, no measuring, no scales, no, camera CG 3/4" behind the center post, no rocket science. Set it once and never deal with it again

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Guys, you are over-complicating things.

 

If you fly the rig with the monitor on the same level as the batteries (Coplanar) and you have that mass balanced both for aft and side to side, no matter what you put on the topstage, how long you make the post or how you set drop time you will NEVER be out of dynamic balance.

 

It's that simple. No Math, no measuring, no scales, no, camera CG 3/4" behind the center post, no rocket science. Set it once and never deal with it again

 

That's EXACTLY what I said. If coplanar; no brainer. And it always was a no brainer if coplanar. No big deal.

 

The ONLY reason Garrett and I got into the whole dynamic balance thing was that Model II's and III's did not have the battery, base, and monitor coplanar. Even today, a lot of us don't, can't, don't want to, etc. have the monitor coplanar with the battery, and if that is so, we have to work a bit harder to achieve dynamic balance. Not much work there either.

 

No one except you, Eric, has suggested that anyone, in the field, measures or uses scales. That 3/4 inch (back of the post) is a good guide for big rigs like the Master Series or the U2, Shadow, Clipper, etc. in a "normal" set up. We do it by a simple and well proven trial and error (empirical) method, a method that works regardless of monitor position.

 

Measuring and scales and the like are extremely important for designers and frankenriggers, as is the mathematics of dynamic balance, so that the designer makes a rig that can be adjusted into dynamic balance in all configurations.

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I have a theory. Neither Jerry nor Eric really exist. I checked with an un-named moderator and it seems that all their posts are coming from the same computer in Beijing China (where all the knock-off steadicams are being made). So I first thought that Eric and Jerry were working together, making these inferior rigs to infiltrate Red users and cause strife on this forum. But with further investigation I believe that they, in fact, do not exist at all -- their posts are the drunken ramblings of a demented Taoist monk. A few hints in their posts have led me to the second conclusion that they do not exist -- Eric once mentioned he was a fan of Rabbit, and Jerry a fan of Pooh...then I remembered this quote:

 

“Rabbit's clever," said Pooh thoughtfully.

"Yes," said Piglet, "Rabbit's clever."

"And he has Brain."

"Yes," said Piglet, "Rabbit has Brain."

There was a long silence.

"I suppose," said Pooh, "that that's why he never understands anything.”

 

In addition to the posts coming from the same computer and the above proof that they are actually one and the same or at least friends, the following clues have led me to this conclusion:

 

First -- numerous times "Eric" has described Tiffen rigs as pooh...which is a compliment for a fan of Pooh such as "Jerry". If they truly hated each other why would one so often compliment the other?

 

Second -- "Jerry's" cable rig uses a steering wheel as a foot rest and as a means to spin the rig..."Eric" loves cars (which have steering wheels) which proves that they are definitely the same person.

 

In China.

 

Drunk and or demented.

 

Trying to tear us apart as a community.

 

by the way "Jerry"...I love "If coplanar; no brainer"...reminds me of Jumbos where they say "Tipsters, not Hipsters". If you ever get over to the states I will take you.

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