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dynamic balance with lightweight monitor?


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#1 Jerry Franck

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Posted 18 June 2009 - 10:59 PM

Hi guys,

I have some trouble to get my rig into perfect dynamic balance.

here's my setup:

- PRO2 sled with Transvideo 6inch HD monitor
- Dionic 90's
- Transvideo Titan on Recoder place

I usually fly a RED or HVX with 35 adapters, sometimes s16 and 35.

I get real close to dynamic balance but not perfect.

I suspect the monitor being too lightweight, not enough to outbalance the 3 dionics.
Any suggestions?
If needed I can also post some pictures...
let me know,

thanks a lot,
Jerry
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#2 Jess Haas SOC

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Posted 18 June 2009 - 11:27 PM

Are you hitting the end of the battery fore/aft adjustment while trying to dynamic ballance? If so then you may need to add some weight to the monitor to get things within range. With no camera on the rig try to get things positioned to where it is slightly front heavy. The two batteries in back will pull the sled back while spinning. Having the cameras center of gravity slightly behind the post counteracts this. In order to have the cameras center of gravity slightly behind the post you need the sled to be able to be adjusted to be slightly front heavy without the camera.

Sorry if that made no sense or was stating the obvious. Don't have a pro rig myself but I did go through the process of converting my rig from CRT to LCD and it dynamic balances just fine. Of course I rarely bother to dynamic balance on set.

~Jess
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#3 Alec Jarnagin SOC

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Posted 19 June 2009 - 12:00 AM

Jerry,

What monitor arm are you using? Highly recommend using one on rails that lets you slide the monitor for/aft if you are not using one already (I use an XCS one on my PRO). Try moving the Titan transmitter to the front of the monitor as well (might need to make a longer cable to reach back around the lower J-Box).
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#4 Jerry Franck

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Posted 19 June 2009 - 01:26 AM

Jerry,

What monitor arm are you using? Highly recommend using one on rails that lets you slide the monitor for/aft if you are not using one already (I use an XCS one on my PRO). Try moving the Titan transmitter to the front of the monitor as well (might need to make a longer cable to reach back around the lower J-Box).


Hey alec,

Yes, I use the xcs bracket too. I have it extended all the way most of the time for better viewing angle and creating somw counterbalance.
Ok, ill try the titan under the monitor, although, I don't think it's enough added weight.

Which monitor are u using? How do u solve this problem?

Thanks,
Jerry
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#5 Fabrizio Sciarra SOC ACO

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Posted 19 June 2009 - 01:36 AM

Hey Jerry,
found the back battery mount on transvideo monitors quite usefull, specially with heavy cameras; with a fourth battery just under the monitor, things goes much easier when dynamic balance is needed and/or for better weight distribution.
Hope it make sense
F
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#6 Alec Jarnagin SOC

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Posted 19 June 2009 - 09:13 AM

Jerry,

I use a TB-6. You can add the fourth battery on the LCD or you can even place the front one there and run a cable (via the AB D-Tap) to the front plate under the post so you are still carrying three. I know some guys just add a weight plate to the back of the monitor instead. Seems silly to add dead weight, but what the heck. Dionics are so light that you definitely need some counterweight with any of the bigger cameras which is what the sled was designed to fly.

Good luck.
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#7 Jerry Franck

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Posted 19 June 2009 - 02:27 PM

Jerry,

I use a TB-6. You can add the fourth battery on the LCD or you can even place the front one there and run a cable (via the AB D-Tap) to the front plate under the post so you are still carrying three. I know some guys just add a weight plate to the back of the monitor instead. Seems silly to add dead weight, but what the heck. Dionics are so light that you definitely need some counterweight with any of the bigger cameras which is what the sled was designed to fly.

Good luck.


Alec,
I now have taped the third dionic 90 on the back of the monitor. It helped a lot, when spinning, it only started shifting after about 20 spins...is that normal?? (I never had my rig total perfect dynamic balance that's why I don't really know...)
when it stops spinning, does it always fall of?
fyi, i had the battery rack all the way in, to the max and two dionics and the titan on it.

Jess,
thanks for the info, I tried it too and it gave me a good idea on where to go from there...
So, why don't you have your rig in dynamic all the time?


does anyone have a video of a perfect dynamic balance sled configuration?

thanks,
Jerry
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#8 Alec Jarnagin SOC

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Posted 19 June 2009 - 08:04 PM

Jerry,

Just remember if you move the third battery to the back of the monitor you will need to run that P-Tap (AKA D-Tap) cable to the front plate as the monitor battery also powers all your video/power Lemos and onbaord deck!

Glad it helped.

Cheers,

Alec
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#9 Jerry Franck

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Posted 19 June 2009 - 09:21 PM

Jerry,

Just remember if you move the third battery to the back of the monitor you will need to run that P-Tap (AKA D-Tap) cable to the front plate as the monitor battery also powers all your video/power Lemos and onbaord deck!

Glad it helped.

Cheers,

Alec




yeah, good point....i guess i have to invest in such a cable...thanks.

Here a picture on how I have it now:
http://img193.images...6/pict0085w.jpg

I got it almost perfectly dynamically balanced.


btw, any of you guys at the gpi event tomorrow?

jerry.
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#10 Jess Haas SOC

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Posted 19 June 2009 - 10:57 PM

So, why don't you have your rig in dynamic all the time?

I know roughly where the weights need to be for dynamic balance so as long as I think its close I don't bother spin balancing unless I am doing something such as whip pans where I feel that it will really matter. If dynamic balance is way off the rig can get kind of squirly but otherwise I don't feel that its that big of a deal for most work.

~Jess
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