2013 New rigs - Real World Improvements?

[Robert Starling SOC]

I meant in no way disrespect to you Robert. I hope you didn’t get that vibe from my post.

 

Not at all Evrim! I'm thrilled you've mastered it and can help. I'd just like to see your quick 2-3 minute high-high build from normal mode to share with some of my students who struggle with sub-ten minute conversions on their multi-section post Tiffen rigs. The forum is all about sharing knowledge and it would be great if you could share how you do it for the benefit of others.

 

As it relates to this thread, many of the new Tiffen rigs for 2013 also feature multi-section posts.

 

Again, it might be better to start a new thread with your video(s).

 

Thanks a million!

 

Robert

[Victor Lazaro]

If your monitor doesn't move from the battery hanger when you extend, my guess it that it's more about the fact that if you dynamically balance with a small post, then the smallest drift will be amplified when spinning.

It's like if you were fore and aft balancing with a 1 second drop time then switched to a 4 second one, your camera will not be perfectly horizontal.

If you obtain dynamic balance in long post, then you should be able to shrink your post and stay with a perfect spin.

 

I may be wrong though, but that's what I think. anyone wants to try?

[Jerry Holway]

Ron, it depends on many factors. Regardless, it is simple enough to get close to good dynamic balance as you extend or compress you rig, or move any components.

 

A few marks on your own rig can make dynamic balance perfect as you extend to preset lengths.

 

For dynamic balance, it does not matter what camera/lens/etc., combo you are using, only the position of the monitor to battery vs. the length of the rig (see the Primer for the logic or, for the nerdy, for the math that describes it).

 

Trimming for headroom (either long mode or short) will put you out of dynamic balance faster than anything.

 

A long post without a tilt head is not very useful. It's a sad fact that I found out the hard way on my first superpost shot when I brought out my "new, ripped apart Master Series, 3 integral posts but no tilt head Frankenrig." Tilting with that rig made the batteries quickly hit things in tight quarters, like behind a lunch counter in a diner, and panning fast while tilted more than a few degrees was a nightmare.

[Jens Piotrowski SOC]

Not the post below the Gimbal...

 

 

 

 

Ron, I believe the fact that mass above the gimbal is moving further away from it makes all the differnce in not being able to dynamically balance it easily. Again you are dynamically balancing the the sled below the gimbal

so if I dynamically balance my rig then extend the post all the way it will be out?

[RonBaldwin]

Hmmm. I understand how much more critical balance is with slower dop times...we have all played with different drops and settled where we like it (I suck so I need a 1 to 2 second drop). I guess I am still confused how lengthening the post will change dynamic balance.

 

So, If I had a U2 nicely spin balanced with a 3 second drop time, then extended the post sections to the max (not moving the monitor, batteries, or their relation to each other) and adjusted the gimbal to have a similar drop, it would not spin flat like it did at the short length? Or visa vesa going from long to short?

 

Pardon my being a broken record, just having trouble wrapping my pea brain around post length affecting dynamic balance. Maybe I have been spoiled running around with a shorter rig all these yrs.

[Jens Piotrowski SOC]

The influence on the Gimbal becomes much more pronounced with distance or leverage.

 

The slightest off balance gets magnified with every additional rotation.

[Eric Fletcher S.O.C.]

The influence on the Gimbal becomes much more pronounced with distance or leverage.

Commonly known as "moment" or "moment arm"

[RonBaldwin]

Yes...I get that the distance magnifies imperfections, but I am asking if post extension changes dynamic balance and doesn't just makes it harder.

[jorge agero]

Some people prefer to go on a Rolls Royce and others prefer to go on a Hunday both are good cars.
But when you see the good drivers prefer Rolls Royce to get around the road that means something.
And more if RR cost the same as the high-end Hunday.
But seriously I have PRO brand products for over 13 years and never ever gave me any problems at all.
And if I had my machine could disarm completely in less than 5 minutes and change the damaged part without sending my team has repaired.
It is essential that you can do with a computer that costs money and which you depend for a living.
Sincerely

Jorge Agero

[William Demeritt]

Ron,

 

As in my understanding, if the monitor and battery are coplanar, and using the "mickey" above, then the CoG of the monitor exerts the same amount of torque as the CoG of the batteries, thus being in balance with respect to each other. If you put this sled on a balancing spud, the sled would sit at perfect horizon (assuming anything above the gimbal had negligible fore or aft mass) and effectively be dynamically balanced.

 

Take any camera, place the camera's CoG directly above the centerpost, and you are still dynamically balanced. The mass above the gimbal has a radius from the axis of rotation being 0, so it's "inside" the axis and exerts no force.

 

Below the gimbal, the mass of the monitor x distance from axis of rotation = mass of batteries x distance from axis of rotation.

 

Since they are coplanar, the distance from CoG of the monitor to CoG of camera = the CoG of the batteries to the CoG of the camera. The effective relationships are an isosceles triangle. Imaging an isosceles triangle spinning in your head, that's effectively a sled with coplanar sub-gimbal masses spinning in dynamic balance.

 

Now, I've been trying to figure out if a sled with non-coplanar sub-gimbal masses enjoy the same benefits, and I think they do? Just the shape of the triangle above is different.

 

Again, ignoring above the gimbal, when the monitor is higher than the batteries, the CoG moves away or the batteries pull closer to the centerpost. Once you find the right position such that, on the "mickey", the mass of monitor x distance from axis of rotation = mass of batteries x distance from axis of rotation.

 

Now, if you place the camera's CoG over the axis of rotation (directly over the center of the centerpost), you should still be dynamically balanced. Camera's CoG is on the axis of rotation, so during rotation, it radius = 0 so torque = 0.

 

When you extend the post, the sub-gimbal masses retain the same relationship to each other, so they still should "balance out". Camera CoG stays over the axis of rotation, so still balanced. The shape of the relationship between the masses is different from the coplanar setup, but it should retain dynamic balance.

 

I would suggest that some confusion comes from working backwards to dynamic balance rather than starting there. I recall that, during my workshop years ago, I was taught to "place the monitor where you want it" and make everything else balance out based on that. The Tiffen method taught me to place the camera CoG over the "back of the centerpost" and then adjust the batteries placement to achieve static balance. After static balance and drop tests, we would then try to find dynamic balance, which inevitably became a game of "nudge the camera... nudge the batteries" one way or another. I remember finding it a few times on the Tiffen rigs, but it just seemed like a lot of guess work.

 

With the mickey, you can find static balance by properly placing your monitor and batteries such that they are in balance with each other, and then add the camera directly over the centerpost/axis of rotation.

 

Anyway, blah blah blah, TL;DR version: extending the centerpost throws dynamic balance out only if the sled wasn't in balance prior to adding the camera?

[RonBaldwin]

Ok...enough of this -- too many notes! If/when my gear ever gets home I will test it out. No super post but to at least full extension of a pro centerpost. It is something I have never noticed and to be honest never been concerned with because I prefer a shorter shed.

[William Demeritt]

I'll bring some brew to help test?

[RonBaldwin]

Ok!

 

edit -- or if you are bored bring your sled over and we can check this out asap

[Robert Starling SOC]

If you guys are doing this next week I'll come over and supervise, act as referee or designated driver as needed.

 

Let me know!

[RonBaldwin]

Sure, but you guys are gonna be bored! Because I will spin balance my rig, extend the post all the way, adjust the gimbal for the same drop, then notice that it still spins flat. All done.

 

Suck it!