Why dedoming a led (newbie general question) ?

Hi dudes.
In several posts people are talking about dedome a led.
Can you please explain me what is the purpose of this ?
(What is the job of a dome on a LED, and why remove it?)

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I think it’s better to make any type of mods, just find the flashlight that you like - what and keep it as “clean” as possible like it comes out from the factory !

Generally, domed emitters have a floody beam and domeless emitter have a spot / thower beam. Some people dedome them to get the tigher beam for a thower flashlight, but that’s not the only reason. Dedoming emitters will also change the CCT and Tint of the beam and to what extent can be different for each different type of emitter.

For example… Nichia 519a with dome has a very floody beam with a neutral tint. Dedoming it will give it a tighter hotspot for more throw. It also lowers the CCT about 25% so a 5700k domed will end up being around 4300k and also lowers the DUV which makes the tint more rosey.

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The dome is a method of gathering and blending the light output from an emitter to both make it (usually) look a little nicer but also to increase the light output (and in that way it’s a similar concept to what we do with reflectors/optics…sorta).

If you look at emitters that don’t have domes on them, you’ll see the yellowish layer of phosphor just “painted” flat on the die (substrate). Depends a little on the type/model of emitter, but the light coming right out the front of that flat surface will be different in brightness and in color from the light that may be coming out of the edges or other angles. So the dome just helps to gather things together a little bit and somewhat control the overall beam angle (for the bare emitter, that is).

That said, the dome disperses light, and a flat emitter surface, while it may not be as pretty or as overall-bright, is usually more intense. Flat emitters can have a little tighter beam when smartly paired with the right reflector size(s) or an optic made to take advantage of that. In removing the dome you lose some lumens, but gain some intensity in the center, and also see a drop in the color temperature and tint. Whether it’s a little or a lot just depends on which emitter.

While some manufacturers like Cree have models in both verions (like an XPL-HD (high density…domed) and an XPL-HI (high intensity…flat) sometimes a dedomed version may be more or less desireable than the original flat version.

When a model isn’t offered in the color temperature that people want, sometimes removing the dome will get them closer to what they desire. Or it’s a good way to play around with beam types and their relationship to reflectors and such, learning about the physics of Light and how everything plays together. By doing this, Our Forefathers had a lot of fun but also eventually brought better and brighter lights to the market, which we can all enjoy today. Pretty amazing how far handheld lights have come even in just 10 years but especially when you look at 15 or more and what we used and modded back then.

Just recently (the last year or so) as the Nichia 519A emitter was introduced, dedoming has become A) Super Easy and nearly risk-free to do, and B) all the rage. Many emitters are difficult to dedome…some of those can be effectively sliced with razor blades, though, achieving nearly the same goals if done well.

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If you have a look through this very old but fantastic LED thread…lots and lots to learn. Way down near the bottom (after the section on UV emitters) are lots of links and there are some for past Dome Threads that are worth reading. The thread is a little out of date now (mostly missing newer emitters) and it doesn’t look like CRX will be updating it, but it’s a really great reference.

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Something else interesting…that very popular 519A emitter has a somewhat unique dome. Instead of just clear polyester or silicone, it has what look like flecks of phosphor mixed in there. I haven’t seen anything in depth on that but I think people said that it has the effect of both increasing light output from the dome as well as further enhancing the color temp and tint. That may explain why we see a little larger change in the light when removing the domes from this emitter than compared to some others.

Maybe along the lines of how many cheapie flat smd emitters these days look like eggs, with a yoke-drop of orangey phosphor in the middle (or sometimes more than one) of the yellow. Small advances that go unnoticed sometimes but have improved the quality of light we see.

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The Primary purpose is to increase throw. In other words, how far the center beam travels.

I have 18 modified lights. All but three of them are de-domed.

By far I prefer an intense Center beam that travels long distances than flood that is only good for a few hundred yards.

Flood lights are good for walking dogs, electricians, plumbers Etc. but I’m unorthodox, although I try to have a flooder on me for aiding me in night photos.

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Yes it really all depends on what you want a flashlight for. For general uses, as in, around the house or walking at night, a domed emitter (in the right light) would be what is best.
For long distances, like spotting predators (two or four legged) , de-domed would be better.
Tint is another consideration. If you are happy with the CCT/tint of a light. Leave it alone. If you feel the need to lower CCT, consider de-doming. But keep in mind, while you might get a little bit better “throw” you will get lower overall output.
The right tool for the job at hand.
Keep in mind, if you de-dome, there is no going back. Well, other than replacing the LED… entirely

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This was an excellent question BTW.

A perfect example on how the newest members can bring value to a foum.

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Again… i don’t find any reason to make modifications on a flashlight… !
Just pick up the right flashlight that fit your needs… and you ere good to go… !

Convoy S21B 6a driver, Nichia 519A Domed vs Dedomed

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Manufacturers have adopted the dedomed concept to the xpl-hi is a dedomed xpl and the sft40 is a de-domed SST-40 emitter .

Simplest answer is de-doming tightens the beam and increases throw .

The 519a emitter is a very easy emitter to dedome .
I 100% disagree with Tartarus comments above . Doing simple mods to lights is a perfect way to get a light much closer to a perfect light for you .
Thinking you can go and buy one will just cause you to endlessly spend money trying to get a better light .
Find one you like the looks of … buy it and if you find you like the feel of it / size weight/ balance etc … Then mod it with your favorite led the beauty of buying budget lights is you can generally open them up much easier .

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