The There Are No Stupid Questions Thread

With lights which are both rated as having similar Lumens, why does one look like it
Has less flux, and the other casts a full bodied beam.

Would also appreciate the difference between candlepower, and Lumens.

I am thick af, so please shine a hefty, clear explanation. TIA!

Candela=intensity of the beam.

Lumens = how many photons the light can actually output.

Simple as that.

Candlepower is an old measurement not used any more.

Candela is about intensity or how light is spread out/concentrated. This is how we measure throw distance.

Lumens are about the total light that is scattering in all directions.

You’ve seen zoomy lights, right? It can change the angle of the beam. Changing the beam angle to be more narrow creates higher intensity or candela even though the led is still putting out the same lumens. So candela changes but lumens don’t.

(Note that zoomy lights are a tricky example to use because their optical efficiency changes a lot as the lens focus changes. The lumens going out the front does drop off a lot as you narrow the beam angle even though the led lumens don’t change)

To give another example, I had two lights with the same reflector size. One with a 70.2 and one with a 50.2 led. In order to get the same intensity, or brightness in the hot spot, I found the 70.2 light needed 1000 lumen while the 50.2 light only needed 600 lumen. So two different lumen levels, but the same intensity due to the different size of the hot spots.

From an earlier post in this thread:

love the alien conversation. my .2 cents is that there are lots and lots of civilisations out there and wouldn’t it be cool if we managed to not kill ourselves long enough to meet one.

now a stupid light question.

say I had a JETBeam WL-S4-GT with a XHP 70 led, and I really really like it, don’t want to mess it up, and don’t have mod experience.

then I see that XHP 70.2 comes out and think, it would be cool to put that in. is it an easy switch? will I mess my light up? is XHP 70.2 much better? (according to a random youtube video it could be).

thanks!

The 70.2 at about 5 amp (I think that’s about the level the WL-S4-GT uses) will probably add a few hundred lumen on max. Not enough to really notice with your eyes. What you will see is the tint difference. The 70.2 is a flip chip design and it creates a yellow Corona around the hot spot. A lot of people prefer the older 70 for it’s nicer tint.

The real advantage of the 70.2 comes when you push it hard, at say 15-20 amps. Then it leaves the 70 in the dust, as it maxes out at about 12 amp.

Another advantage of the 70.2 is it has a smoother hot spot with only a faint dark center. The 70 has a noticable dark center (when used with SMO reflector). Your light uses a orange peel reflector so you won’t see much difference there.

I would not bother swapping it out. If you wanted to try, it’s as easy as ordering a new led on a similar size mcpcb and swapping it. I’m guessing it’s a 6v unit. Verify that before ordering. Then you just solder the 2 led wires. Pretty easy.

hey thanks Jason!! got it.

Is it possible to use SST20, LH351D and Nichia 219C together in a direct drive setup for tint mixing? Would they differ much in brightness or burn due to different forward voltages?

The LH351D and SST-20 would not be a problem in this setup, since the high CRI variants have very similar VFs.

The 219C would cause problem however. don’t know how much.

Yes, that is what I supposed. I wanted to try the SST20 and 219C 5000K together to increase rosiness and get a 4500K tint. They would get around 3 - 5A per led. Do you think the 219C would draw more current than is good for it?

So I might need to mix LH351D and SST20, throwy in the center and floody outside, not bad either.

You really need a wider CCT variance than 1000K to lower duv significantly. Most 5000K, 90+ CRI 219C bins are pretty green anyhow.

Why don’t some of the more expensive brands have lvp built in

Expensive does not mean better.

That aside, you might need to be more specific.

It just seem sensible feature to me extra safety but I understand you shouldn’t just rely on it. I was just thinking why they wouldn’t include it, i would not use one without lvp when using Li-ion Batteries even protected ones.

All the expensive lights I know of use it. What is an example that you know does not have LVP?

Recently tested a new zoomie by Wuben.

While it has both the throw, and the clarity, the convex lens doesn’t seem to have
The photon density of a comparable reflector.

Would appreciate knowing why a reflector casts a much more robust circle of light. :beer:

Most “zoomie” designs waste a lot of light when the LED is highly focused because there is no reflector or TIR optic to capture what is shone to the sides.

Both of the latter capture almost all of the light an emitter produces. I would say “photon density” sounds like intensity/candela though, and zoomies can actually still blow away reflector or TIR lights of the same bezel/head size.

Like BurningPlayd0h said, it’s about optical efficiency. Typical zoomie efficiency between wide angle and narrow angle can be a factor of 3. It might put out 900 lumen in wide mode, but only 300 lumen in narrow mode. It has terrible efficiency but it can still be pretty intense and throw a long distance.

Did we answer your question, because I’m not sure what you were asking about.

Thanks for your responses.

To my eyes, when focused on a distant object, the convex lens throws well, and the
Object can be seen clearly, but it seems like a flat projection while a reflector’s
Light seem more robust, and illuminates with what seems like a more intense beam.

Is it possible a deep reflector throws most of the photons into the projected beam, while the
Zoomie is less efficient in doing so. With losses. In arcs of artifacts :question:

Not unless the lens or focus is completely f*’ed

Reflectors tend to put about 50% of OTF light into the hot spot. The other 50% goes into the spill.

Zoomies put maybe 30% of the light into the narrow focused beam. Something like that. If it’s focused exactly, they basically project an image of the led die. There is no coma or corona around the edge like with a reflector hot spot.

Maybe the perfectly straight columns of light from the projector/convex lens gives that flat appearance. The reflectors columns of light are not perfectly straight. It tends to blend the beams of light together more for a smoother hot spot. IDK, just guessing.