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Powering 3 cameras over long distance

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John Barata
Powering 3 cameras over long distance
on Jul 14, 2013 at 8:58:11 pm

I produce a live sporting event where I run 2 handheld cameras and 1 on sticks. I have always powered the one on sticks using the power converter/battery charger for teh camera (All cameras are sony PDW-800).

My 2 handhelds are connected to me so I can watch, direct and also lock timecodes. I was thinking I could build a 100' 4 pin xlr cable to run to each from their battery charger/power converter which would stay by me. This way we never have to break a camera during live action due to his battery dying.

This seems simple enough in my head but I'm sure there are a few things that can trip me up. Any help is much appreciated


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Chris Tompkins
Re: Powering 3 cameras over long distance
on Jul 15, 2013 at 12:33:15 pm

Funny you use the word trip...
That's a lot of cord hanging around a public sporting event.
Do you move around?

Can you stagger the battery changes between the 2 cams?

Chris


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John Barata
Re: Powering 3 cameras over long distance
on Jul 15, 2013 at 3:18:11 pm

They move around a bit and have cable pullers to insure that they don't trip anyone. Either way they will need to stay wired for video and timecode purposes.

We have had them change batteries in opertune moments but since we rent the cameras and batteries every so often we'll have a battery that goes from 100% to dead in 5 minutes which is always fun to deal with in post.

Since they have to remain wired for other reasons my thought is why not just run power up the cable with everything else and then there is never a worry about the battery dying.


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Mark Suszko
Re: Powering 3 cameras over long distance
on Jul 19, 2013 at 2:50:12 pm

Well, the longer the run, the heavier gauge copper you will need to run power, or it will get hot. I'm not an electrician, but the long run will I think put a strain on the power supply, which has short cords for a reason.


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John Barata
Re: Powering 3 cameras over long distance
on Jul 20, 2013 at 3:15:57 am

Does anyone know of another solution to this? Is there another power supply I can be using? Or should I just suck it up and use batteries


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Mark Suszko
Re: Powering 3 cameras over long distance
on Jul 20, 2013 at 5:02:56 am

Well, in the old days, when puppies were the oldest animal, and we recorded onto long strips of mylar infused with rust particles... our batteries were HEAVY, short-lived nickel-cadmium cells, and you wore a Chewbacca-like bandolier or belt of them, connected by a big, coilly cord to your camera and/or 1k camera light. Of course, the cameras were steam-powered, and we all wore an onion on our belt, being the fashion at the time...

(comes back from geezer reverie with a start)

*! um, so... yeah, get higher-capacity batteries, or you might have to wire something up from individual cells, and put it in a backpack or fanny pack for the camera operator or cable-puller to wear. Look at the power draw of the camera with everything on, then figure the amp-hours you need to run non-stop for your longest anticipated event. Then have a guy at a store like Batteries Plus wire something up custom for you.

If that sounds crazy, well, maybe, but running 100-200-foot AC stingers to each camera in a venue that may have lots of foot traffic around... sounds just as bad to me. Most people in your position with a higher budget would cut ALL the cords and use wireless feeds from the cameras back to the director. With backup iso records in each camera, you can fix a blown live switch in post, or use the live cut as a guide for the final version.


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John Barata
Re: Powering 3 cameras over long distance
on Jul 23, 2013 at 4:00:25 am

The cables aren't really in many peoples way. We don't run them where the public is walking so I'm not concerned about that especially since I have to run cables either way. From what I've read it's very do-able but i need some very large gauge cable. Just trying to figure out how thick.


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Drew Lahat
Re: Powering 3 cameras over long distance
on Jul 23, 2013 at 8:06:05 pm

It's very doable and I've done it before. Not sure what's all this talk about wireless... sure if you're running steadicam or are on a motorcycle in the Tour De France you want wireless, but generally field productions prefer wired links where you have constant and reliable power, comms, video, genlock and CCU between the camera and the truck, and you never have to deal with batteries at all. Of course you have to run the cables safely but it's done everywhere all the time.

As far as power, you want a good gauge for the amperage, but don't forget about voltage drop. These charts and calculator will help you a lot:
http://www.powerstream.com/Wire_Size.htm
Remember you can utilize multiple pairs as the load will split between them - as long as you can fit the strands into the XLR4 connector solder cups...

I worked with Sony EX1 cameras, which thankfully take industry-standard 11-17V power (like the PDW800). I shopped for laptop AC power supplies (which are very clean) and chose ones towards the higher end of the voltage range, based on the calculated loss per the planned wire run. (If you have a 50ft run and a 150ft, I'd label and always match the power supply to the cable.) At the camera end the voltage was towards the lower end (~13V) which is just fine.

I wouldn't run AC power. Running 100ft of AC power alongside data is supposed to really screw up the signal with interference...


I did all this 4 years ago when I built an HD multicam solution for a church. To meet the budget I created custom cable assemblies which carried power, HD-SDI, and intercom to the cameras similarly to a professional cable. I used multipair wire from Gepco. Panasonic later came up with their own (relatively) affordable multicam solution which is similar to mine, just more professionally built and with a CCU:
http://pro-av.panasonic.net/en/sales_o/broch_pdf/StudioSystemCTLG.pdf
(Not sure though why Canare went with a mesh bundle jacket instead of a multipair assembly.)
Professional OB trucks run SMPTE hybrid fiber which uses the fiber for data and copper leads for high-voltage DC (for those 1000ft runs). Nowadays JVC owns the budget-multicam niche with some well-integrated solutions.



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John Barata
Re: Powering 3 cameras over long distance
on Jul 27, 2013 at 9:51:40 pm

Thanks for this Drew. Your on the same thought process as me. I had thought of the ac adapters too but wasn't sure if that was a viable solution. With your info and some other info I got techs it looks like this is the best way to go. Now it's time to start making cables.


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Drew Lahat
Re: Powering 3 cameras over long distance
on Jul 29, 2013 at 3:44:15 am

A couple of shots of the cable system - feeding HD-SDI camera, return, intercom, power, and tally.




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