I know, I reread my original post and got it mixed up. My question is better stated as why does the lumen brightness double and the CD and beam distance barely increases.
Thanks to you guys I know that it's because the surface area (2 LED's instead of one) is greater which increases the overall light output but not the brightness of the individual LED's and also the reflector is way more important for throw than brightness is.
Joey, I saw some prices and it'll be a while before Vihn ruins all other lights for me but I can definitely see making a major purchase from him in the future. Maybe the D40 Tmack was talking about, That sounds impressive.
Think of it this way:
An ordinary 100 watt light bulb might put out 1800 lumens, and, if you screw it into a table lamp, it might light up and area with a pool of light the size of a large room. To make the math easier, think of the pool of light as a circle on the ground about 100' in diameter if we use the ANSI standard 0.25 lux (Using as example, didn't do the math).
So, if the circle of light on the ground has a diameter of 100', it means the throw is 50' (The radius).
That's 1,800 lumens with a throw of 50'.
Let's now screw the same bulb into a reflector, and, instead of a round pool of light all around the bulb, we have a cone of light, all projected out in one direction. So, we have concentrated those ~ 1,800 lumens INTO A SMALLER AREA. Lets say the reflector's beam is now putting a pool of light that is narrower, but longer....on the ground.
Making the beam longer increases the throw and the cd (Throw and cd can be the same thing).
Now we take a reflector that focuses the beam even tighter, so, its even narrower, and longer, than the first reflector's beam. The longer beam has even more throw, and so forth.
We are using the same lumens to get massively different beam shapes.
Now, in practice, the things that make one beam fatter and shorter, and another longer and narrower, are quite varied.
For example, the depth of the reflector can increase throw, as can the diameter, and, the geometry of the reflector bowl for that LED.
The smaller the phosphor size is relative to the bowl size, the more the LED acts as a better "point source". What that means is that the optics of a reflector bowl theoretically work best if the light is emitted from a single point A point as used in geometry, with only one dimension). The less "point-like" the source is, the more spread out the photons will be as they ricochet around in the bowl. So a larger LED is less "point-like", and, all else being equal, will have less throw...and so forth.
When an LED is dedomed, it makes the LED emit from a smaller surface area, and, therefore, more "point-like"....which, for most LED, can about double a light's cd.
Another clarification:
A light's cd is its lux at one meter.
A light's throw RANGE is the distance at which the beam intensity drops down to 0.25 lux on the target (The sensor of the light meter).
Using the inverse square law, you can calculate a light's RANGE from it's cd.
Because, in a nut shell, the inverse square law says a light's intensity (lux) on a target will be 4x lower at 2x the distance, or, 4x brighter at 1/2 the distance....it means to be 4x brighter at the SAME distance, its cd would need to be 4X as much, but to be the same BRIGHTNESS at TWICE the distance (Have twice the RANGE), it would have to be 4X brighter as well.
So, doubling the cd doesn't double the range, it just doubles the brightness....but the brightness needs to be FOUR TIMES brighter to double the RANGE.
I know, that's confusing...but just remember "
4x brighter to throw twice as far".
So, cd IS a measure of "Throw", but, throw can be in terms of cd (Brightness, as in lux at one meter), or, range, (in terms of meters).
So, if you say you are doubling the throw by going from 100 k cd to 200 k cd, you are, in terms of cd....but not in terms of range. (Doubling the cd would be more like a ~ 50% increase in range)
