Reflector vs. Aspherical Lens

[deerndingo]

Hi Guys,
I'm brand new here. Gee you guys know what you are talking about.

I just bought an EDI-T P3 led torch. It has a focusable lens. For a torch about the same size as a mars bar its incredible. The guy who sold it to me said that it is that bright because it has no reflector.

Whats the go with that. Can someone please explain how that works. I thought the larger the reflector the more light thrown out.

Thanks in advance

 

[deerndingo]

Hi,
Anyone got any thoughts on this.

thanks

:thinking:

 

[Freeze_XJ]

Well, a lens focusses light (think magnifying glass, remember burning things with it?), and a reflector does exactly that, only by reflecting light in the right direction instead of bending the lightbeams. The effect is about the same, with some limits. To focus tighter (for better throw) you need a larger reflector, or a rounder lens. On the other hand, the larger your reflector, or your lens, the less light will go astray, so throw efficiency goes up (and spill-beam goes down!). Most lens lights do have a small reflector, to ensure light emitted sideways is directed to the front as well by the way. It's just a matter of choice.

 

[IMSabbel]

Well, also, one reason why for LEDs aspherics are better throwers (compared to e.g. incans or HID) is the radiaton pattern.

Leds direct most of the light forwards natively. This means a reflector will need to be very deep (in addition to the diameter) to capture a significant amount of the light, while even a small lens will get a big fraction.

 

[Gunner12]

As said before, a lens focused the light into a beam, like a reflector. A reflector focuses the light coming from the side of the LED, so the brightest part of the LED's emitting pattern goes to the spill.

In most cases, the lens collects more light from the LED then a reflector does, since the LED projects light forwards, and not as much sideways. This makes the hotspot brighter and thus throw further then a reflector. But unlike a reflector, the light that doesn't hit the lens doesn't become spill, so the beam will only consist of the hotspot.

Much of the above is from my logic, not actual knowledge, so it might not be accurate.

:welcome:

 

[deerndingo]

Hi Guys,
OK, that explains it. Now I'll post a question about who makes focusable LED torches that can go from spread to hot-spot.

Thanks

 

[bigchelis]

Hi Guys,
OK, that explains it. Now I'll post a question about who makes focusable LED torches that can go from spread to hot-spot.

Thanks

There are $15 dollar DX variants and $600 ARC Mania custom builds with many others in between.


What you want to spend?

how big do you want it?

bigC

 

[yellow]

still have the link here:
http://www.dealextreme.com/details.dx/sku.14450
posted it in Your other thread as well ...


just want to type: aspherical lights are "superior" in just a single department: throw

when the (totally spill-less) beam of that focusing thing lights are set to the size of the main beam of a reflectored light, the reflector light eats the aspheric and at the same time the reflectored one offers useable spill, while there is no light at all around the aspheric main beam.