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Powering location light/s


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#1 Jed Shepherd

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Posted 22 May 2011 - 07:13 AM

So ive read a fair bit about this but I cant find the best answer.

I have a shoot in july which has a night scene in it. I will have a 1.2k hmi available as my main light source (poor student film, best we can afford) and im trying to work out how to power it. Unfortunately i have the dialogue dilemma which makes using a generator a problem. I have looked into silent generators but they still seem to give off 50+db of sound at around 4 meters or so.

My question is, If i hire a 5-6kva silent generator (more then what we need by a lot but just taking start up wattage into account) could I effectively place it far enough away from the light by using a long extension cord without any issues? I know using long extension cords creates problems but I would prefer not to go down the deep cycle battery with inverter road as its cheap to rent a generator but not to buy a battery and inverter.

The dialogue is my main concern as we arent skilled enough to get decent ADR happening yet. Just wondering what other people have found works in a similar situation to what im in.

Any help would be great.
Thanks
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#2 Adrian Sierkowski

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Posted 22 May 2011 - 07:32 AM

you have voltage drop with long runs, which causes you to use thicker cable is all. You could use a typical put put far enough away with nice thick cable.

This table should help:

http://www.cerrowire...ault.aspx?id=51
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#3 Sean Elder

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Posted 22 May 2011 - 09:10 AM

I think from the information that you have posted, you should be fine with running the genny and keeping it at a distance. I've had the same issue with a film I shot earlier this year. The issue we had was about the sam, lighting subjects where there was quite a bit of dialog, but since we were using Sony wireless lavs, (which don't always work around police stations, for some reason)the genny sounded more like an air conditioning unit which can be easily taken out or down in post. We had the genny roughly a city block away from the lights we used (Arri 1K Tungstens) and we had no problems what so ever. I hope that this helps, but I'm pretty sure more people will chime in with their experiences! Have a great day!


So ive read a fair bit about this but I cant find the best answer.

I have a shoot in july which has a night scene in it. I will have a 1.2k hmi available as my main light source (poor student film, best we can afford) and im trying to work out how to power it. Unfortunately i have the dialogue dilemma which makes using a generator a problem. I have looked into silent generators but they still seem to give off 50+db of sound at around 4 meters or so.

My question is, If i hire a 5-6kva silent generator (more then what we need by a lot but just taking start up wattage into account) could I effectively place it far enough away from the light by using a long extension cord without any issues? I know using long extension cords creates problems but I would prefer not to go down the deep cycle battery with inverter road as its cheap to rent a generator but not to buy a battery and inverter.

The dialogue is my main concern as we arent skilled enough to get decent ADR happening yet. Just wondering what other people have found works in a similar situation to what im in.

Any help would be great.
Thanks


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#4 Adrian Sierkowski

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Posted 22 May 2011 - 09:18 AM

I should add; that you need to remember that with HMIs, there is more draw than just the Watts (e.g. 1K is not = to 10 Amps.)
An older ballast can draw up to 18A of power when striking (magnetic) and the electronic ones will be around 13~15ams.
It's draw should be noted on the ballast itself and you need to heed how much it draws and how much you have per breaker per outlet on the genny and also factor that in to your line drop calculations/cable choices.
Guy Holt is very informative on these things, and I suggest shooting him a PM or checking out his website, @ screenlightandgrip.com. There is a lot of information under the "generators" section.
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Opal

Tai Audio

Media Blackout - Custom Cables and AKS

Wooden Camera

CineLab

Rig Wheels Passport

rebotnix Technologies

Glidecam

Willys Widgets

Visual Products

Aerial Filmworks

Technodolly

Metropolis Post

Paralinx LLC

CineTape

The Slider

FJS International, LLC

Broadcast Solutions Inc

Gamma Ray Digital Inc