Night shoots with a generator

Discussion in 'Professional Video Production' started by Will L., Apr 18, 2005.

  1. Will L.

    Will L. Guest


    I'm preparing to shoot a night scene out in the woods. My problem is we
    have a Coleman Powermate 3000 watt generator for the shoot but my word
    is it loud. Does anyone out there have any experience with this? Our
    wireless mics are pretty good at not picking up the sound but I need to
    know what the maximum length of extension cord I can use in order to
    get the beast as far away as possible.

    Then there's post. Anyone got any good suggestions for EQ'ing or
    elimanting the sound in post? Unfortunately the talent includes some
    men with low voices which I am afraid means we can't just roll off the
    low frequencies without affecting the dialogue.

    Any thoughts or stories would be greatly appreciated.

    Will L., Apr 18, 2005
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  2. There have been discussions about mitigaging genny
    noise over on newsgroup. A couple that might be useful to amateur
    productions might be: throw old blankets, mattresses
    around it (but not close enough to catch fire!); Build a
    hedge around it with bales of hay. Borrow (or rent)
    a lot more extention cords. Use big commerical ones
    so you can go hundreds of feet, etc. There are plenty
    of references you can find online, etc that will tell you
    what size wire you need for different loads (wattages).

    Realistically, don't plan on removing ANY of the genny
    noise in post production. The pros either eliminate it
    at the source, or else the replace the entire dialog track
    by dubbing it (ADR).
    Richard Crowley, Apr 18, 2005
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  3. Will L.

    David McCall Guest

    The bigger the cable the better. It might be usable at
    200'-300' if you did 2 runs of #12 cable, and made
    sure all of the connectors were clean. The main issue of
    long cables is that all cable has voltage loss.
    15A, @ 115v, #6 AWG wire, 200' = 3 volt drop
    15A, @ 115v, #12 AWG wire, 200' = 12 volt drop
    15A, @ 115v, #12 AWG wire, 300' = 18 volt drop
    15A, @ 115v, #14 AWG wire, 300' = 28 volt drop
    15A, @ 115v, #14 AWG wire, 500' = 47 volt drop

    Reduced voltage will cause tungsten lights to be oranger
    You could use an autotransformer to boost the voltage
    up before sending it down the wire.

    Another approach would be to do dialog replacement
    in post, then the generator could be near the set.

    David McCall, Apr 18, 2005
  4. Will L.

    nap Guest

    Although.. if you have a noisy generator, make sure you get samples of the
    noise at each setup with no other audio. When I have that in post it is much
    easier for me to remove via noise reduction plugins. Often I can cut it from
    the production track but I have had situations where I could not. But I can
    surely say that I only have to do that when the production absolutely can
    NOT do ADR. Or the actor is gone. or whatever.. And it can be a painful
    process. For me that is. 'Cause it never really sounds right, thank god for
    that music track, or the train in the distance or the traffic SFX..
    nap, Apr 18, 2005
  5. Will L.

    Seattle Eric Guest

    Obviously, distance is your friend. Get REALLLY heavy-duty stingers
    and put that sucker as far away and around as many corners as you can.

    "Heavy duty" residential type stingers are the SMALLEST you should go:
    much better would be rent them from a grip house- they're cheap.
    I like the hay bale idea. One thing is, you want to re-direct the
    genny noise upwards, w/o restricting access and air-circulation, so a
    hale-bale chimney might be good. Especially if it's far, far away.

    Borrow (or rent)
    According to the DVD extras, virtually ALL dialog on the Aussie show
    "Farscape" was ADR'd, which is amazing if you're familiar with it. You
    need some absolutely fanatical hot-shit sound engineers to make this
    really good. Not to mention skilled actors.
    Seattle Eric, Apr 18, 2005
  6. Will L.

    John Rowell Guest

    Instead of using the generator, how about using several heavy-duty golf
    cart type batteries along with a 3000 watt inverter? Then you'd have no
    noise at all. Just a thought...

    John Rowell, Apr 18, 2005
  7. Will L.

    C.J.Patten Guest


    I'm sure you can dampen the sound - the hay bale chimney idea is great and,
    of course, really long extension cables. (put a couple hundred feet between
    the gen' and you plus the hay - might not even hear it.)

    Plan around topography. A low rise between you and the noise helps a lot.

    I like the idea of a battery array. I've done this in the past when the
    generator was too noisey.
    Between takes or on breaks, we'd fire up the generator and charge whatever
    battery source we had.

    They make LED based lighting rigs these days that are amazing on power.
    You might rent or buy some of those. How much light are you spraying around?

    Also: you CAN rent silent generators. We had them at an airshow last summer
    and you really couldn't tell they were around. Lord knows how they work but
    they did. Try event/tradeshow rental companies.

    C.J.Patten, Apr 18, 2005
  8. Will L.

    NerdRevenge Guest

    Sand bags dampend the sound best out of anythign I have heard. Even next to
    a generator all you hear is a sputter
    NerdRevenge, Apr 19, 2005
  9. Will L.

    Tim Mitchell Guest

    Silenced gennys just have a large acoustic enclosure round the engine
    with lots of eggcrate foam and baffles for the cooling etc.

    They have 2 problems:
    1-they are extremely big and heavy because of all the acoustic padding
    2-they are way more expensive to hire (and to get to site as you need a
    big truck with a crane)

    Most film lighting companies have their silent gennys permanently truck
    mounted, they just drive them to wherever is required.
    Tim Mitchell, Apr 19, 2005
  10. This sounds stupid and crazy ............. and of course, I've done it.
    It's only a 3k genny, right?
    Buy 20 feet of clothes dryer vent hose and put the genny in the back of a
    van that is parked as far away from the set up as possible.
    Run the hose from the muffler to an AWAY side window. Open the window just
    far enough to feed the hose through.
    It works.
    Just be sure to open the doors every 20 minutes more or less so as to let
    the genny cool down.

    It that is too scary, then rent or buy a 3K inverter for your car or truck's
    battery. Using the vent hose on the exhaust pipe works well enough, as long
    as the car is as far away from the set as possible.

    Bill F.
    Bill Farnsworth, Apr 19, 2005
  11. Will L.

    Will L. Guest

    Will the voltage drop result in a loss of wattage or something more
    nefarious in the electrics? I'm thinking if I drop the number of lights
    I might be able to pull a 200' run without any harm. I want to throw
    about 2800 watts worth of light around, gelled to that 'fake' blue
    moonlight that's as bright as the sun. But that may not be an option
    and I think I can work around it. So if I can't score the super heavy
    duty cable can I get away with an 18 volt drop to provide 1500 watts
    off the genny?

    The battery idea does sound pretty cool. Just too much stuff to buy and
    test, if I had a month or two I'd investigate. Plus it sounds like I
    would need a much larger crew just to haul all those batteries down
    there. I'm shooting on 55 acres of land so I am sure I can find a
    depression I can mount the genny in so that might help. My only concern
    with the hay chimney is the genny does not have a spark arrester on it.
    Seems like I would be begging for trouble with that much hay. ADR is
    simply not an option. I have a pretty intense hatred for it.

    BTW my lights are three quartz 600 watt lights and two 500 watt
    flourescents, all from NRG. Flories can be switched to 250 watts and I
    have replacement lamps for the quartz to get them down to 250 as well.
    No tungsten unfortunately but I'm lucky to be making movies at all so
    I'm not complaining.

    Will L., Apr 19, 2005
  12. Will L.

    David McCall Guest

    Quartz lights come under the heading of tungsten. I think most
    (maybe all) lights that use a filament have tungsten filaments.

    The voltage loss over a long run will reduce the brightness and
    color temperature. One problem with color temperature loss
    is that the lights will become orange, and orange is directly
    across the spectrum from the blue that you want to gel your
    lights with. Blue gels cut your light output dramatically when
    the light is putting out it's proper temperature, so the loss of
    intensity will be quite dramatic with an 18 volt loss. I don't
    know if the flos will even strike with that much voltage loss.
    Even trying to color correct the orange lighting to look blue
    would kill your video levels (I'm not sure if correcting in post
    would even be better than gelling the lights, but it might.

    You can rent cables from any mopic or theatrical lighting company.
    Cables are about the cheapest thing to rent. #12 cables wit the
    right connectors (or adapters) would be really easy. #6 cables
    with adapters might be somewhat more difficult to come by,
    but not impossible.

    There's always day for night :)

    David McCall, Apr 19, 2005
  13. "Will L." wrote...
    Meaning what? If by "electrics" you mean only incandescent
    (halogen, conventional, or otherwise), then the only downside
    is lower output and lower color temp. Your fluorescents, OTOH,
    may be more sensitive to power source droop. I think I might
    have a voltmeter on hand to monitor the situation.

    OTOH, if by "electrics" you mean electronic equipment, I would
    either use a really good UPS or run a separate extention cord
    all the way to the generator for the electronic load(s).
    Its not going to harm incandescent lamps no matter how much it
    droops. Have you done a location scouting trip and established
    that 200 feet away is sufficient to mitigate the sound? Sounds
    dubious to me. (No pun intended.)
    That will make it a whole lot worse. You will lose a great deal more
    light with those blue gels than you will through the extention cords.

    Have they seriously considered shooting "day for night"? Even
    pros with big budgets frequently just bypass your whole scenario
    by filtering the camera with blue and shooting at the right time of day.
    Richard Crowley, Apr 19, 2005
  14. Will L.

    Will L. Guest

    I can't shoot day for night as there are some power antennaes or cell
    phone towers in the background whose flashing red lights are necessary
    for the scene. They won't be on during the day, at least not visible.

    I have scouted the location and here are some pics if you want to take
    a look.

    I'm hoping the abandoned concrete building will provide some muffling
    for the sound and I am using lav mics which should also help out a bit.
    As for extension cord I am considering Coleman Cable 100 Ft. 12/3
    Contractor Grade Extension Cord, UL listed. 12/3 AWG, meets OSHA
    requirements for outdoor use. I don't want to rent as we own the genny
    and need to compliment it with appropriate cord. If anyone knows where
    I can order something better please, please let me know.

    Thanks so much for the help everybody!

    Will L., Apr 20, 2005
  15. IMHO, it would be a great deal easier to "paint" in the light flashes
    than to try to shoot at night.

    Your location appears to be an AM radio transmitting site. Assuming
    you have tried your video and audio equipment there to confirm that
    the high RF fields won't interfere?

    And assuming you have permission from the owner/manager (right!?)
    have you asked them for temp access to their power source? Even
    paying them for the electricity is worth not having to deal with the
    genny sounds. At least try to get the genny inside that garage (with
    metal dryer vent to take the exhaust out under the garage door.)

    Do you have any friends/cast/crew who works in construction?
    They might be able to borrow some beefy extension cords.
    12-gauge seems kinda wimpy for your load at that distance.
    According to the previous posting by David McCall, you will
    get >12V droop which is pretty significant, especially for the
    fluorescent and electronic loads.
    Richard Crowley, Apr 20, 2005
  16. Will L.

    Seattle Eric Guest

    As an animator/post-FX person and sometime gaffer, I agree.
    Seattle Eric, Apr 21, 2005
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