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How to get a tight spot of light (4 ft diameter at 15 ft)

Discussion in 'New Member Board' started by Learning, Dec 14, 2004.

  1. Learning

    Learning Member

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    I'm looking for a way to create a fairly tight spot of light (~4' diameter at 15 ft.) I currently have PAR38 fixtures and I'm getting ~15ft diameter spot at 15 ft with a "flood" light. Will a PAR "spot" light get me <6 ft at 15 ft?

    Also, what's a ray light kit? Would this help narrow/focus the beam?

    Any (relevent) suggestions would be greatly appreciated!
     
  2. sound_nerd

    sound_nerd Active Member

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    you wont be able to get too narrow of a spot with par38's. the par "spot" light will help a bit, but it still might be around 10ft diameter @ 15' throw. The raylgiht kit converts the par fixture from taking a standard "par" bulb, to taking something different, im not sure which kind of bulb it is off hand. Nor am I sure if the raylight kits are even available for a par38. The last par28's that I used just had a standard "A" base ceramic socket.
     
  3. len

    len Well-Known Member

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    Best way is to get barn doors. Probably going to be as much as the fixture costs but what can you do. The only other way is to get a leko.
     
  4. avkid

    avkid Not a New User Fight Leukemia

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    par-spotlight(no!!!!!!) get a fresnel or two and barn doors for those!
     
  5. JahJahwarrior

    JahJahwarrior Active Member

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    try a Par 16 Birdie can, that might work too, but it won't give you tons of ight. like, in lumens.

    Raylight kits use the DYS lamp, about $6-10 at most companies, local or mail order, and the lamps have a life of 75 hours.
     
  6. Learning

    Learning Member

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    Thanks all! Any favorite sources for fresnels?
     
  7. techieman33

    techieman33 Well-Known Member

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    NO NO NO, don't get a fresnel, if your going to rent/borrow/buy something, get an ellipsoidal, or a source 4 par, those can make a pretty tight beam if you have the smooth lens in them. fresnels, make bad specials, they don't have a hard focus at all, the source 4 pars are a little better, but your best bet is to get some kind of an ellipsoidal.
     
  8. SketchyCroftPpl

    SketchyCroftPpl Active Member

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    What if you used like really this plywood or black plastic and a compas and made a hole in the wood or w/e so that it was the right size at 15ft. It would be kinda hard to make it perfect but I think that you could do it especially if you used a drill or something like that and it would be alot cheaper than going out and buying a whole new light
     
  9. ship

    ship Senior Team Emeritus Premium Member

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    Plywood in being flammable won't make a very good donut as is described by SketchyCroftPpl. Also given the nature of a PAR lamp, you can't really add a donut with ensuring the spill will be proper.

    A say 100w PAR 38 NSP lamp will have a beam width of 2.62' at it's beam angle - that point where the field angle of the beam drops down to 50% given a beam perpendicular to the surface. This thanks to the free GE Light Beams program. Differentuate the spill field angel of light at less than 50% intensity from the field angle that's down to 10% light. That less than optimal light you can clean up.

    The PAR 38 spot in most cases for a say 100w lamp, will have the foot candles on the surface of 75.6fc. Remember however you are not lighting the floor, you are lighting the talent that is about five feet above the deck. This means that the intensity at a now shorter distance will be a smaller angle. The beam angle of 10 degrees on a PAR 38 will only be about 1.75 feet at 10'.

    Remember however that perpendicular distance is different than hang angle distance to the stage in being a trigonomitry factor of A(2) + B (2) = C (2) in being the diagional angle to the surface in not even accounting for the second use of this figure due to the angle to the center line of the stage.

    Given these two factors, your distance will probably end up being about your requested three foot in dia. given the fixture type.

    Most ray lights work on a four instead of the spot's 10 degree beam angle. It's field angle is even more narrow in no chance of spreading at this distance sufficiently. Such lights won't work well at this distance. Most ray lights will be set up for a PAR 36 instead of PAR 38 anyway which while it might fit within the fixture once you cut a slot for a PAR 36 lamps' keyway, it might also not. Wiring on such a ray light fixture is also dependant upon the manufacturer but expect it won't just screw in.

    Also there is AR-111 lamps in the size of a PAR 36 that are like ray light lamps only they have both lamp and reflector plus a exterior center filament shield included in them. Such lamps also would conform to about a PAR 36 iin being just 1/4" less in dia. but for fixture size would have a better output than a PAR 38. There is a 8 degree versions of AR-lll available that would get similar to a beam angle on the PAR 38 spot.

    Say on a 8 degree AR-111 from Philips or Osram having 48,000 Candlepower at 100 watts/12 volts - (you provide the transformer), verses say 40,000 Candlepower for a 250w PAR 38 lamp as the largest PAR 38 available and something that might melt down the wiring to the PAR 38 fixture. Sorry but I don't have the figures for a ray light output given it's normally too small of a beam angle anyway.

    Beyond these, if your light fixture can accept a PAR 36 lamp, one might install say a FBE lamp into it that has a 5,000K color temperature and 36,000 Candlepower, or a FBO that has 3,400K and 67,000 candle power for a 25 x 15 degree beam of light. You can expect the normal color temperature to be about 3,200K. Granted you would have to barn door or mask the beam in some way due to it's slightly larger than wished for width. Black Tack Tape - a adhesive backed black aluminum foil tape works well for this in creating barn doors, otherwise City Theatrical should have some PAR 38 barn doors on the market.

    The barn doors or top hat in lengthing spill light clean up of the beam of light will clean up a PAR beam as opposed to a donut that encloses the light beam but relies upon a Leko's control of the beam to control beam angles not at the gate it's limitating.

    In other words, a few small coffie or large soup cans will form a better control of your light beam than a donut/plywood circle on a PAR lamp. Also when in addition to a donut such a top hat will help with a Leko.

    Why go with a spot lamp instead of a MFL? While you can cut off the beam angle by way of barn door or top hat, the intensity across the area at a certain distance will be much less than the intensity of a lamp with a smaller coverage in area due to a set amount of light given off distributed across a narrower angle.

    An alternative to these lamps might be a #Q4631 PAR 36 sealed beam lamp. It has a beam angle of 13x12 degrees which is right in your 15' figure, and a candle power of 80,000 candlepower. Granted you have to get a transformer that will run a 250w/13v lamp.
     

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