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Hybrid Brushless roll cage on top of Steadicam.

movi steadicam

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#1 Abad Rosa

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Posted 01 January 2014 - 10:05 AM

Has anyone seen the hybrid roll cage that some operator is developing to keep the horizon flat? It sits on top of the sled, and just keeps the horizon flat. I think it's AlexMos based. I've been looking around to see if I can find it, but no luck so far.


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#2 Jarrett P. Morgan

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Posted 01 January 2014 - 10:34 AM

you mean like the AR or Omega Revolution? 

 

http://www.thomaseng....uk/mk-v-ar-rig


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#3 Charles Papert

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Posted 01 January 2014 - 02:35 PM

Ha, just spent half an hour thinking about just that today. What makes more sense than a roll cage is a section of a roll cage, i.e. a short arc that would eliminate, say, 5% of roll error. Package it up nice and tidy with a power cable and on/off switch and build it to sandwich between dovetail and camera (bonus points if the top of it can grab onto the various manufacturer's dovetails, so it is a quick-add accessory for shots that require it). Theoretically you could do a separate shorter length version that would weigh less for more experienced operators as their roll correction would need to be less than a novice. It should have minimal weight but it would raise the gimbal by a nominal amount. More elegant would be to build it into the rig, a la the Tiffen tilt head, with the ability to switch it on and off if needed (and a mechanical clamp lock to eliminate vibration when not in use).

 

A lot of experienced operators would hate it, of course, because a) they pride themselves on their horizon never being a problem and B) it levels the playing field, literally and figuratively. The fact is that nearly all operators come up against a situation where a little bobble can come through now and again, so it wouldn't be the worst thing to have ready to go in a case. And the fact is that stabilization whether on set or in post is here to stay and only going to become more widespread, so might as well go with it.


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#4 Alan Rencher

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Posted 01 January 2014 - 06:52 PM

That's funny. I had the same exact thought.
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#5 RonBaldwin

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Posted 01 January 2014 - 07:18 PM

I'm in Charles...I need all the help I can get on my downward spiral!!  Nowadays I can only get work if I pay for post stabilization, which comes out of my equip rental.  If I can spend a fraction of that cost on a gizmo that helps me hold a horizon...I AM ALL IN!!


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#6 JamieSilverstein

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Posted 01 January 2014 - 09:36 PM

I'm buying in too.
Keep it simple and cheap.
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#7 Lawrence Karman

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Posted 02 January 2014 - 01:19 AM

So would a horizon correcting leaning camera body on a stabilized roll axis cause the rig to get even more out of balance and require even more correction, possibly reaching the limit of the roll axis? Or could one hard fist the rig with that type of device on there?


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#8 Charles Papert

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Posted 02 January 2014 - 01:29 AM

I'm sure as hell no physics expert but it seems that if the arcs are the proper radius, the camera would roll around its center of gravity and thus it shouldn't affect the balance of the rig. The tricky part is that cameras can have widely varying relationships of height to CG so a one-size-fits-all arc would be difficult. If someone else can chime on this who knows the actual science, please do.  


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#9 Andre Trudel

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Posted 02 January 2014 - 01:47 AM

First thing I thought of when I saw the Movi. 


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#10 Abad Rosa

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Posted 02 January 2014 - 08:54 AM

Found it: https://www.facebook...&type=1


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#11 Abad Rosa

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Posted 02 January 2014 - 09:52 AM

If enough people are interested, I will put my go pro gimbal on my efp and auto stabilize the horizon as a proof of concept. Could also do a 2nd go pro shooting the gimbal so you could see the correction being put in.

 

For now, enjoy this short vid of the gimbal taped to a line on a four point rig. You can see the amount correction being put in if you observe the line at the top of the frame which is what the gimbal is gaffer taped to.

 

http://www.youtube.c...h?v=wACSpkc1oP4


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#12 flemming laybourn

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Posted 02 January 2014 - 09:58 AM

@ Charles: thats one of the challenges of working with the AR.. even if the camera is leveled of like a normal rig, as soon as you start putting the rig "off level" and the camera starts to move inside the rig, new forces appear. If the cameras mass is not centered inside the ring, the camera will get buttom or front heavy depending on where the mass is placed inside the ring, when you fx try to tilt with the rig at a horizonal position..
So any hommade system should include the possibility to lift and lower the camera inside the ring...

( reading back my mail to myself, im not really sure if it makes sense..? )

flemming
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#13 Charles Papert

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Posted 02 January 2014 - 10:11 AM

Yes Flemming, that makes perfect sense. The bummer of that is that you have to make the assembly capable of managing the tallest or most top heavy camera and everything else has to be shifted upwards to re-center, so more likely than not you are pushing many cameras that much further from the gimbal. Time to revisit Lyn's original concept of putting the roll axis behind the camera...?


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#14 JamieSilverstein

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Posted 02 January 2014 - 10:49 AM

Is this a stupid idea?

Instead of putting the roll axis behind the camera, or worrying about it changing due to height differences between cameras, why not try to put the roll axis in the middle of the camera?

Possibly (and I am no engineer so forgive me my naivete) create a bracket that fits around the lens mount and the center of the camera where the battery or back plate sits.  If the roll axis is centered on the camera, then shouldn't the response be the same where ever you put the camera and the rig in space?


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#15 Benjamin Treplin

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Posted 02 January 2014 - 12:29 PM

I think a one-size-fits-all-arc would do the job. For a ± 5 deg capable arc it doesn't matter that much if the camera CG is centered dead on. You can overcome the effect of the changing balance by a faster drop-time, which would be okay as you don't have to worry about having a perfect level anymore.

Lynn's concept of mounting the camera on an L-shaped bracket would work nice with light and short camera bodies (Epic), I think. With an Alexa and heavy lenses the bracket must be extremely rigid, equals heavy, and the whole contraption would get very long.


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