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Battery solution for EFP w/ Arri Sr3

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#1 Matt Pope

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Posted 05 October 2004 - 05:16 PM

I'm a student at a film school that has a Steadicam EFP. Admittedly, I don't know much about the rig, but whenever I see it being flown on students sets here, it's always tethered to a big block battery (which is itself dragging an AC). I think to myself, that can't be the way it should be done.

According to others around here, the reason is: We are using an Arri SR3 w/ video tap that requires a 24volt power source. I'm told the battery on the sled will not power the camera, tap, and steadicam monitor on its own. When I ask why the on-board battery isn't used for the camera & tap, I'm told it makes the rig too heavy.

Is this a valid point? Is there no better way to fly an EFP w/ an SR3 camera than to drag around a big block battery?

Also, a little unrelated - I'm only likely to have this rig in use for a week or so, but I'd love to have access to a wireless tap solution. I'd certainly love something like a modulus, and may very well rent one, but I keep wondering if anyone's ever tried one of the $200ish UHF transmitters that various "spy shops" or places like www.rf-links.com sell in conjunction with a small handheld Tv like the 5" radioshack handheld? Obviously the quality and performance wouldn't compare to a professional solution, but would it even be an option (for someone with no money like myself?)

Thanks in advance!

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#2 RobVanGelder


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Posted 05 October 2004 - 08:58 PM

The EFP is originally a 12 volts model, so that is why it cannot power the camera, unless it has been converted.

One option is to work with 2 NP-1 batteries, attached to each other in series by 2 connector caps that are sold by PAG or other vendors. These batteries are light and will power the camera for a reasonable time. attach them to the bottom of the sled with elastic bands or tape.

A wireless link made from those cheap transmitter and receiver systems can work very well, specially on short distances. But expect some local surveillance camera┬┤s on your channel, sometimes. Also it is always illegal but in the real world nobody really cares....
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#3 Ramon Engle

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Posted 05 October 2004 - 11:05 PM


Matt, the SR# is made to run with onboard batteries. There is a small metal adapter that plugs into the xlr battery port and the onboard batteries fit onto that. Unless you have really weak springs in the arm the EFP should be able to fly the SR3 without being tethered. Is Michael Lines going to operate for you?

Good luck.
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#4 Michael Tien

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Posted 08 October 2004 - 08:39 AM

:) Check this out as an alternate way to get 24v to your camera.


I ran an SR3 with this Vicor converter for 2 months. If you buy one you will need the connectors. My AC used the plastic box it shipped in as a case. It will power the camera and video assist no problem. I initially ran my BFD off of the 24v to 12v converter on the camera but that puts 3 devices on the Vicor and it didn't like it. I had a y cable made for the 12v out on the sled. One side was for the Bartech and the other for the Vicor. Make sure you pull off the eyepiece heater cable.
My rig maxes out at 25lbs so having the on-board battery would put it over the edge.

Michael Tien
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#5 IanMcMillan


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Posted 12 October 2004 - 02:56 PM

Hi All,
This is probably to late but I can't see why you can't run on boards for the camera and split and rig bats for monitor and accs. The EFP arm should be able to cope and the batteries and camera should be able to handle the power situation. If its a 12V tap then power the tap off the Rig.
All the best
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#6 costasflex



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Posted 13 October 2004 - 06:59 AM

The arm should handle the weight of the sr3 and bat on board depending also on the lens it carries.Ihave flown on on my sk2 with a wide light lens in the past and I was at the top limit, but it was ok flies ok. :)
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