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Arc lamp question

Discussion in 'Lighting and Electrics' started by lightbyfire, Jun 16, 2007.

  1. lightbyfire

    lightbyfire Member

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    So I have a rig of studio spot CMYs, and saturday/sunday matinees. I have exactly two hours from the end of the matinee to channel check for the evening performance. I am wondering if it is worth it to douse the lamps or will the restrike reduce lamp life by more than two hours?

    The studio spot is equiped with power save when the shutter is closed.
     
  2. JD

    JD Well-Known Member

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    2 hours? Its probably better to shut it off. I don't know that there have been any formal studies, but arc lamps work best one hour on / one hour off. (Last I read.) With the douser closed there is a bit more heat retained and that can reduce life as well. I'm sure there will be a lot of opinions on this, but I usually use the 30 minute rule of thumb. If its going to be idle for longer, I shut it off. I am not familiar with the power save mode on that light, that may change things.
     
  3. icewolf08

    icewolf08 CBMod CB Mods

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    General rule that I was taught with arc lamps is that each strike is about equivalent to an hour of burn time. Thus, if you are going to have more than an hour where you are not using the fixture then it is worth destriking the lamps. If you are going to be on a break shorter than an hour then leave the lamps lit.
     
  4. jonhirsh

    jonhirsh Active Member

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    If you are going to leave them on, put them in open white with the douser/ shutter at 100% open. W/ pan and tilt in the home postion.

    It is the better for the lamp.

    Second I would leave them on. Things fail most offten on start up and shut down.
     
  5. zac850

    zac850 Well-Known Member

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    If you leave them on, don't close the shutters. Open shutters, open iris, pointed either in home position or up into the theater somewhere out of the way not blinding anyone. Better for the light, doesn't have the two hours of heat building up inside the fixture.

    Second, two hours for me is the break even point, anything more and I would douse, anything less and I wouldn't......... flip a coin, its probably about the same for the lamps either way.
     
  6. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    As others have said, leave them on and shutters opened. Two hours is not that long...if you had 6 hours between shows then I may say to lamp off....but 2 hours leave them on... As was noted--lamp strikes will take hours off your lamp life and the capacitor in the unit...or so the manufacturers claim...

    -w
     
  7. lightbyfire

    lightbyfire Member

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    Ok thanks to all of you. I'm going to leave them on and open since ive had problems blowing lamps on restrike.

    I had just wondered whether the power save mode makes more sense? according to the manual it drops the wattage down when the shutter is closed to reduce heat and power draw, but the idea may only be for short term blackouts not on an hour scale.
     
  8. jonhirsh

    jonhirsh Active Member

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    You run the risk of overheating the fixture if you leave it closed. This can lead to damaged dichroics, and gobos.

    JH
     
  9. JD

    JD Well-Known Member

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    Yea, they don't tell you this, but often the shutter is the last thing on the light chain so light and heat are blasting the filters, gobos, and everything else in the fixture even though there is no output. (btw, often true with follow spots as well.) A good point to think of during the show as well. I have several "standby" scenes programmed in my board so that when the lights are not on they have no gobos or filters in, just the shutter closed. Anyway, I usually leave them in this mode, and then switch to a loaded black scene right before I execute. Kind of like the old Warning, Standby, and Go on follow spot cues.
     
  10. jonhirsh

    jonhirsh Active Member

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    It makes sense, you dont want to focus on the shutter assembly. Why would you take that time to program that in? Is it just a macro you wrote or do you have a ton of programming time. To me it just seems like a extrem extra step to protect rental gear.

    JH
     
  11. JD

    JD Well-Known Member

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    I guess the priorities are different if you own the equipment. The shutters are flat blades of metal at the front of the fixture, not much to get damaged. If you have a color engaged, then the full lamp output is still going through the diachronic and/or gobo even though there is no fixture output. Diachronics do have a life span, and glass gobos that use diachronic filtering do as well. In each of my scene banks, I have a scene set up white/no gobo/shutter in. This produces the least wear and tear on the fixture. Only takes a few seconds to program in, and its a once and done thing. When they are not being used or there is a break in the show I simply bump that scene.
    Also, although they use forced ventilation, it is still better to land them in a kind position when idle.
     
  12. jonhirsh

    jonhirsh Active Member

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    Yes i think you care more when you own them :)

    What board are you using?

    JH
     
  13. JD

    JD Well-Known Member

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    I use a number of boards. They are not Hogs! ... more like what would be found under the tail ;) I have a windows based controller that runs on my laptop, and a few stand alone bank controllers like the Chavuet DMX 55. I also have this weird habit of using a separate board for movers, next to my regular board. (Don't ask me why, but it works for me!)

    Simple actually works better for rentals. You preprogram the scenes during sound check, then just tell the LD what buttons to push. However, I think if I found 20 grand laying around, I would pick up a Hog ;)
     
  14. jonhirsh

    jonhirsh Active Member

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    The reason i was asking is to determine weither you are using a tracking or non tracking board. Because if you were using one it would seem like your causing your self more trouble then its worth.

    JH
     

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