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attaching prston mdr/arri to donkey box


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#1 richard bellon

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Posted 28 June 2010 - 02:35 AM

Hi All

sorry if this has been discussed before but i cant seem to find info on it.

Probably a silly question but when one mounts the mdr to the donkey box, it adds mass to the camera, now obviuosly one must slide the camera back to balance but is there some system/ rule of thumb in terms of placing cameras i.e 3/4" from the center of the post that one can use as a starting point?

thanking u all
rich

Edited by richard bellon, 28 June 2010 - 02:37 AM.

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#2 Robert Starling SOC

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Posted 28 June 2010 - 09:21 AM

If you're attaching it to the Donkey Box it adds mass to the sled not the camera.

There are numerous posts on static and dynamic balance to help you.

Robert
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#3 RobVanGelder

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Posted 28 June 2010 - 11:12 AM

Though it does not add weight to the camera, it is for sure adds weight in front and above the gimbal and therefore needs to be compensated with the placement of the camera and monitor/battery system.
Basically you mount everything above the gimbal as close as possible to the post. Also accessories on the camera should be as close as possible to the camera and near the post.
The Preston is in normally fixed on its place and should be considered part of the rig once mounted. The motors however are more variable in weight, size and placing.

Then with the placement of your monitor and batteries and the full camera set you can adjust and find the static and dynamic balance..... sounds simple but every rig is different and there is not really a rule of thumb, I think.

But the one rule of thumb you could find is that dynamic balance is often reached when the CG of the camera set is approx. 1 to 2 inch behind the center of the post.
YMMV... :)

Rob
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#4 RobVanGelder

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Posted 28 June 2010 - 11:12 AM

Though it does not add weight to the camera, it is for sure adds weight in front and above the gimbal and therefore needs to be compensated with the placement of the camera and monitor/battery system.
Basically you mount everything above the gimbal as close as possible to the post. Also accessories on the camera should be as close as possible to the camera and near the post.
The Preston is in normally fixed on its place and should be considered part of the rig once mounted. The motors however are more variable in weight, size and placing.

Then with the placement of your monitor and batteries and the full camera set you can adjust and find the static and dynamic balance..... sounds simple but every rig is different and there is not really a rule of thumb, I think.

But the one rule of thumb you could find is that dynamic balance is often reached when the CG of the camera set is approx. 1 to 2 inch behind the center of the post.
YMMV... :)

Rob
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#5 richard bellon

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Posted 30 June 2010 - 03:38 PM

thanks for the replies
its all appreciated

kindest
richard
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#6 Lohengrin Zapiain

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Posted 06 July 2010 - 07:54 PM

Hi All

sorry if this has been discussed before but i cant seem to find info on it.

Probably a silly question but when one mounts the mdr to the donkey box, it adds mass to the camera, now obviuosly one must slide the camera back to balance but is there some system/ rule of thumb in terms of placing cameras i.e 3/4" from the center of the post that one can use as a starting point?

thanking u all
rich

I usually start with the camera 1 inch behind the CG, get my static balance right and then try spinning test to get the dynamic balance right. With heavier cameras, and to be more specific 535 and f900 with Panavision lenses (witch are more or less the same pain in the back) I start with the CG right in the middle of the center of the post, otherwise I run out of room to move my batteries back and never get DB.

Hope this helps :)
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#7 richard bellon

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Posted 09 July 2010 - 02:57 AM

Hi All

sorry if this has been discussed before but i cant seem to find info on it.

Probably a silly question but when one mounts the mdr to the donkey box, it adds mass to the camera, now obviuosly one must slide the camera back to balance but is there some system/ rule of thumb in terms of placing cameras i.e 3/4" from the center of the post that one can use as a starting point?

thanking u all
rich

I usually start with the camera 1 inch behind the CG, get my static balance right and then try spinning test to get the dynamic balance right. With heavier cameras, and to be more specific 535 and f900 with Panavision lenses (witch are more or less the same pain in the back) I start with the CG right in the middle of the center of the post, otherwise I run out of room to move my batteries back and never get DB.

Hope this helps :)



hiya

thanks for that, every little bit helps.
the heaviest camera i had on my rig was the Arri St, such a beast.
thanks all for the info
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