Two bulbs one reflector??

Hate to start first post here with a question but that is admittedly why i joined. basically long time lurker first time poster.

Anyway, I have been pondering the idea of having 2 HID bulbs in the one reflector which needs to be quite compact like a 6 or 7 inch diameter, I'm just wondering how it would effect the beam and direction and throw and all that kind of stuff. Its for a hand held marine application.

I have had a good quality HID hand spot light in the past it was a 200w, It was quiet powerful and very long throw however had terrible spread and was a very narrow beam. so my thinking is two bulbs in the one reflector should make a lot more punch.
Surprisingly i havent found an answer to this question anywhere.

kind regards, Stobby :wave:

If you did that, it would not be a spotlight. Reflectors can only create a narrow beam from a point source that's located at the focal point of the reflector. The larger the source (longer arc or filament, larger LED), the wider the minimum beam width, because more and more of your light source is farther and farther from the focal point. By the time you get far enough away to allow for two bulbs, you won't have much of a beam left.

Now if you were talking a very large reflector, it would be a different story...

Usually the position of the bulb is shifted to the deph of the reflector.
if you want both spill and throw from one bulb/LED look at frosted lens / orange perl reflector

so in order to get a more intense beam and more spread i would need a stronger single light source? which would only leave the option of short arc xenon bulbs as i don't believe these automotive hid's can be cranked up anymore then 200w.

Do you mean that you don't want a narrow beam? Or do you want a narrow beam and some "spill" to illuminate the area around the light? Spill is the light that comes straight out the front without hitting the reflector.

I would really prefer more spill then what most spotlights have. The previous spotlight i owned had a large 9" reflector and barely any spill it was a very narrow concentrated beam. http://www.ebay.com.au/itm/9-inch-2...288425?hash=item4ae9c085e9:g:HdEAAOSwPCVX44v-

so would two light sources create more spill and more of a spread out beam?

There are some lights that use a 2. very small reflector for spill

it is also possimble to get a frosted lens in front to create additinal spill

stobby said:

I would really prefer more spill then what most spotlights have. The previous spotlight i owned had a large 9" reflector and barely any spill it was a very narrow concentrated beam. http://www.ebay.com.au/itm/9-inch-2...288425?hash=item4ae9c085e9:g:HdEAAOSwPCVX44v-

so would two light sources create more spill and more of a spread out beam?

Click to expand...

Think of how the spill is generated. In a perfect reflector, it's light that doesn't hit the reflector. So to get wider spill, you move the light source toward the front of the reflector. To get brighter spill, you either need a brighter source, or you need to steal some from the beam. The frosted lens that Lexel suggested would do just that.

Now about the beam. In a perfect parabolic reflector, an infinitesimally small light source exactly at the focal point of the reflector would create a beam that is perfectly collimated. That means that all the light (except for the spill) is going out parallel, and it would create a spot exactly the size of your reflector no matter how far out you go. Short arc sources with big reflectors can come remarkably close to this. But that's not what you want. As you move the source forward or back along the axis of the reflector away from the focal point, the beam will become wider and wider.

Also, as your source gets larger and larger, the beam gets wider and wider.

As you move the source off the axis of the reflector (which you have to do to put two sources in one reflector), the beam gets distorted. I'm guessing you probably don't want this.

Your goals are not difficult to achieve. You are not pushing the edges of the possible, but rather taking a big step back from the cutting edge. I would think you could achieve what you want in two ways.
1. Take a nice bright emitter and experiment with pushing it forward and back from the focal point. Once you get the beam you like, check the spill. If it's not enough, add a frosted lens to increase spill.
2. As above, but instead of adding frosted lens, add a second emitter (and preferably a second reflector) to get the spill you like.

Ok thanks for all your input and ideas guys, I will have to experiment with a few different setups and see what i can come up with.

Out of curiosity does anyone know how hard you can drive a H3 HID bulb and how many watts you can pump into it reliably?