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Portahead 10 brushless gimbal with Arri Alexa on steadicam

brushless gimbal alexa brushless stabilized head

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#1 AndreasKielb

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Posted 14 August 2014 - 02:40 PM

First application of the Portahead 10 prototype for a short film. The system is designed to be used with a steadicam system as portable device and adds electronically stabilized roll and tilt while the pan acts manually with the steadicam. The weight of the 2-axis head is 3.6 kg and it is optimized for longer cameras at around 10 kg like the Arri Alexa series or Amira, Red one, Sony P1 or F55 with raw recorder. Shorter and lighter cameras can also be used as the motor output settings can be adjusted.

 

Later there will also be an additional pan-motor in order to extend the system to a 3-axis stabilized head for crane, cablecam or car-to-car shots.

 

 

www.portahead.de

 


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#2 Mariano Costa

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Posted 14 August 2014 - 03:41 PM

Woohah! That's quite a beast! Congrats! :-)
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#3 Jens Piotrowski SOC

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Posted 15 August 2014 - 01:56 PM

What is the purpose?
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#4 Mariano Costa

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Posted 15 August 2014 - 03:45 PM

What is the purpose?


Looks like it keeps the horizon leveled but doesn't interfere with the pan axis.
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#5 AndreasKielb

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Posted 15 August 2014 - 03:56 PM

There are a lot of reasons. For me auto-leveling is not only to make moves like with the AR and from low to high mode. It's more to bring an extra level of perfection where it is needed and even if it's not. There are shots where a sway in horizon is absolutely disturbing, like for instance a packshot for a commercial or a tracking shot through an empty hall at super wide angle. Other shots are more forgiving like if there is a lot of movement in the picture. But I think if the technology is there, there is no reason to make compromises. Often the reason for an error is not even apparent in the picture, like a difficult terrain, but most errors are just disturbing. Why not use a technology that makes every steadicam shot look like a dolly shot?

 

Current sensor technology has a precision unreachable even for the jedi master of steadicam. The possible angular resolution of the mainly used Invensense MPU 6050 is 0.06 degrees dynamic and 0.02 degrees static ( http://www.basecamel...ownloads/32bit/ ) and is almost in a range of the fibre optical gyros. For comparrison the new digital level displays are set to 0.6 degrees or 0.3 degrees although technically much higher resolutions might be possible ( http://www.steadicam...orizon_whm.html  ). But at those highest resolutions even the slightest gimbal handgrip would cause the level display to go crazy and unreadable.

 

On the other hand the combination of steadicam and brushless technology creates an effect well known from Cineflex or the Stab C head. Those expensive systems utilize an outer axis which does a pre-stabilization like a normal 3-axis head but then 2 or sometimes 3 axis are stabilized once more in order to create a high sensitive inner axis system. That's why those systems are called 5-axis or even 6-axis stabilized heads.

 

The combination of steadicam and gimbal could also be considered a multi-axis system. The steadicam already creates a very stable picture with an angular precision of maybe between 0.3 and 0.8 degrees, if fast starts and stops are taken into account but are compensated by hand from an experienced operator. Of course way better than with a handheld gimbal. This supports the high sensitive inner axis (gimbal) in an excellent way. It doesn't need to try to correct large errors and shows therefore much better results than a handheld 3-axis gimbal could do (less micro-vibrations). Actually a win-win situation for both systems and the operator.


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#6 Jens Piotrowski SOC

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Posted 15 August 2014 - 07:31 PM

Adding 3.6kg (8lbs) for roll stabilization seems odd, all you will add is fatigue for the operator, look how long the sled is...and the shots in the video are better done without it...
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#7 AndreasKielb

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Posted 15 August 2014 - 10:53 PM

I was the operator in the video. The weight of the camera and the head together were about 14 kg, I think. My arm handles about 23 kg with that springs and it was not completely at it's max which is about 15 kg camera weight.

 

I know that those scenes can be considered as easy and every operator is estimated to do them without any problem. But the shots were already planned with normal steadicam and I was asked to do them longer before. Then we were talking about my electronic stabilizers and the idea came up to finish the almost complete prototype during the week and to make a first test on Friday. That test went well and we decided to go for it for the actual scenes. There was never the idea to change the already planned shot designs only for this test. For me it was a great chance to actually try the system with the Alexa for the first time and I'm just happy that everything worked well so far.

 

There will be another project next week and also I hope to be able to use the system during an upcoming feature where I'll probably work as b-cam and steadicam op. With a little luck there might be shots that show off the potential better, otherwise I'll need to pull off a shooting on my own, later.

 

Both axis, roll and tilt are stabilized and the antler like length of the setup creates much inertia to bring the manual pan axis to a higher precision level as well. I think at least the lock off in the beginning is a little more locked as usual, but that might just be my own wishful thinking.


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#8 Jens Piotrowski SOC

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Posted 16 August 2014 - 12:14 AM

Who is operating the actual stabilized head? You or somebody else? And how do you coordinate the movements?
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#9 AndreasKielb

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Posted 17 August 2014 - 09:34 AM

The steadicam operator also controls the head with the same movements as with conventional steadicam. The pan axis is directly connected to the sled and therefore operated completely manual. The tilt is set to a really tight follow mode and is following the movement of the sled very closely, as the operator tilts the sled up or down. It feels like normal steadicam operating and the tilt also reacts precisely to slight headroom changes. It's common praxis with the steadicam to compensate fast changes of the subject with a boom up or down with the arm rather than a tilt, like if an actor is taking his first step down on a flight of stairs. It would still be necessary to do compensate such movements with an height change of the arm rather than tilting but I never felt that I was too late with framing even though the head reacts milliseconds slower than with a direct mechanical connection between sled and camera.

 

It's even important technically that the steadicam operator controls tilt on it's own because the space under the camera is limited and with a remote operator not paying attention the risk of getting in touch with the topstage accidently would be too high. The system can tilt 90 degree up and down and those movements  would be impossible to synchronize with a remote operator. Therefore it's solo operating only if the head is connected to the sled.

 

If the head is extended with the optional pan motor to build a standalone 3-axis head, the systems settings can be changed without connecting a laptop by clicking the menue button twice. This preadjusted profile is set to wireless remote control and also controls the additional pan motor. As you can imagine from the heads dimensions, tilting 90 degrees down will be impossible in that configuration, only the the tilt of the steadicam sled together with the whole head opens the necessary space for the camera to tilt 90 degrees. But I see it as a  benefit for car-to-car shots regardless, that the 3-axis version can be strapped to a frame by bungee cords without the necessity that somebody actualy holds the head at higher speeds. This simple rigging solution opens a new field of applications with the portahead 10 and Alexa, which needed a shotmaker and stabilized head before.

 

I already did a number of car-to-car shots in the last year with the smaller Portahead 5 and cameras like the Red Epic. These are two examples:

 

http://www.porsche.c...ult.aspx#/intro

 

12.jpg

 

 

For the Porsche footage we also did the aerials with the rc helicopter of the DP and a small brushless gimbal adjusted by me and with the blackmagic pocket.

The car-to-car shots are in the chapters 3 and 4. For the other clip I only did the car-to-car scenes while the aerials were shot by another company.

 

 

 

http://www.portahead.de


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#10 AndreasKielb

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Posted 17 August 2014 - 10:17 AM

Another possiple application with the Portahead 10 would be pack shots like in the showroom chapter of the Porsche footage. In this special case it was necessary to do it with the dolly because there were a lot of breaks inbetween the move to show the different features (lights on and off, back door open...), DP and assistent had to stay on the dolly calmly for the entire morning. But we had to use curved and liniar tracks in combination as the curved tracks alone have a radius which is too small to set it up around a car. Thats why there was a lot of post stabilization necessary to compensate the nonuniform flow. If the shot were just a half circle without the technical stops, the shot would have been even easier and smoother with a system like the Portahead 10 in combination with the steadicam.


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#11 Jens Piotrowski SOC

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Posted 17 August 2014 - 03:07 PM

wouldn't this be a much more compact solution for horizon stabilization?

 

Attached File  XCSroll.jpg   59.45KB   26 downloads


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#12 Marc R. Berger

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Posted 18 August 2014 - 03:09 AM

Hi Jens, where did you find this? What´s that? Something like this new WXB level assistant? From XCS...can´t find it listed on their website.

Thanks,

Marc


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#13 Jens Piotrowski SOC

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Posted 18 August 2014 - 07:43 AM

This is a project Greg from XCS was working on and exists in prototype form but was not released to the public.


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#14 Martin Hawkes

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Posted 18 August 2014 - 08:19 AM

kid_candleblow.gif


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#15 Justin Besser

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Posted 18 August 2014 - 07:21 PM

I wish this existed.. Would love a solution for working on OB sporting/outdoor events dealing with windy/adverse conditions in a live environment.. Needs to be able to handle an ENG or p2 camera system + link
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