[PART 1] Official BLF GT Group Buy thread. Group buy officially closed! Lights shipping.

pommie great beamshot, Totally believable as well based on my experience.

That’s why I’m such a stickler about using open licenses — to make sure everyone can use it and it won’t be vulnerable to profiteering legal trolls. In general, no good comes from people trying to own ideas.

I’m waiting for a builder to build an adapter for a LED light that can mount it on the eyepiece end of a long focal length telescope. In decades past I would take an ordinary incandescent FL and shine it through the eyepiece of a 8” F10 cat’ ’scope to point out what we were going to be looking at next. Imagine the beam with a really good light! I might try that with the H4. Next stop Alpha Centauri. Of course it gives up something in portability, but built right and on a simple 2 axis mount while it wouldn’t be terribly portable it would be able to be used anywhere in the hemisphere of which it would be the center of at that moment.

The problem with this is that telescopes are made with a very narrow fov, so very little light coming from an LED actually gets used.
I’ve considered telescope mirrors for making a superthrower, but they just collect too little light from the eyepiece.

This is pretty much the case for any kind of telescope.
The angle of light that would get used from the LED is like 15 degrees or something super tiny.

Wow now that’s a light . You can hit satellites with that .

I am curious, does anyone have a CAD of a waiven collar or know how to make one?

If we could get a good CAD design for one it is possible it could be 3D printed and mylar or a reflective coating added for testing at least.

The first step in any waiven collar project would be a CAD design of the collar itself. Getting it made should not be that difficult really.

It translates to something like “Pfffffttttt LOL”

I’m still curious if it’s feasible to add a reverse-wavien reflector to a traditional reflector light. It’d be the same idea, bouncing extra light back at the emitter to increase surface brightness… only it’d use the wavien’s negative space to reflect the spill part of the beam back so it can bounce into the primary reflector.

The tricky part is holding the thing in the right place without blocking much of the parabolic reflector.

It’s possible, just not very practical.

First of all, the wavien collar collects about 75% of luminous flux from an LED based on it’s collection angles, and this increases the intensity by about 2x.
The amount of spill from a typical reflector is 25% of LED lumens.
With an efficiency of about 33%, such a collar would only increase the intensity by ~1.1x
This is of course assuming you have a high precision cold mirror collar, not some home-made polished metal ball section.

Also, since the “collar” would be in the middle of the reflector, the useful front area is reduced when compared to a lens of the same diameter with nothing blocking the middle.

Overall, the result would be about the same lux as a lens setup without a wavien collar, and half the lux of a lens setup with a proper wavien collar.
It would collect more lumens though, since 75% of light would be directly output without touching the collar, whereas with a typical lens+wavien collar only about 25% of light exits directly, the other 75% goes to the collar.

It seemed like it’d be tricky at best, but it’s nice to see some quantified estimates. Thanks!

Yeah, they’re just rough estimates but it shows it certainly won’t make a huge difference like adding a collar with a lens does.
What *will *make a difference (although I don’t know how much) is having a collar with a smaller opening, however that would require a completely different thread to discuss since it would be a lot of theory and calculations.
Maybe some day I will have spare thousands of dollars to buy custom made spherical reflectors and test out the idea.

Enderman I’ve done it with a much lesser light than we have available today. If I remember correctly it was a 2 cell incandescent and nothing special. The beam was incredible out the end of the ’scope. I remember it being bright and a very narrow beam. But I had night adapted eyes too. Folks looking had no problem following it into the sky to see what we were going to look at.

That’s a newtonian pictured. I used a 8” F10 2000cm FL (I think that’s accurate) catadioptric. I don’t know if that makes a difference but it’s easy enough to find out when I get the time to get the telescope out. I might also have a lenser FL still hanging around. That should narrow the beam up to get better efficiency. It might also prove it to be an utter failure but that’s what experimentation is all about. But I do accurately remember what I did 2 decades ago.

“bright” and “narrow” doesn’t really give enough information…
I don’t doubt that you can see it, it’s just that numbers are what matter here.

If you want to take a luxmeter and do another test with a telescope then go ahead, but I can guarantee you that it will not be in the millions of lux.
Maybe in the hundred thousands if you’ve got a large diameter telescope.

A long focal length just makes a straighter aka more collimated beam, it doesn’t actually increase lux, even though it looks cool.

I understand that. I made no claims as to lux. Only that the beam was bright and narrow and that I used it as a pointer and that it was easy to see, all other words leading to more were not used by me. The scope I used was definitely not magical or somehow produced light internally.

The gist of the post was to see (basically) if others here had tried it or had an interest in trying it. I know that it worked (that wasn’t the issue), and it wasn’t unique to me. I got the idea from others in “Astronomy” magazine. So I know that it worked for me as well as others.

The Alpha Centauri comment was just a joke. Obviously I don’t have a fusion source that can outshine Sol nor a way to concentrate the light to beam it anywhere.

I have tried with LED flashlights and small telescopes/binoculars/monoculars.
Yes it makes a nice thin beam and super tiny spot, but it sucks for lux, and the amount of lumens coming out is next to none.

Hi guys, long time BLF reader. The GT looks too impressive to pass up so it’s finally time to sign up.

Can I still get into the group buy?

Yes for $150 as the $111 is already filled up. The Miller will chime in soon to update the list.

Welcome to BLF.

Welcome to BLF

Will update the list later.
You are in the groupbuy for $150

Just paid for the 120mm lens. If it increases the lux of my GT without much modification, I’ll be a happy. Otherwise, well, it happens. I don’t have any immediate plans to put new driver and emitter in the GT, I think the large amount of lumens (for a thrower) is part of the fun.

I have a few leds on the way for my 2 other throwers, a maxtoch 2x, and a uf-1508. Hope I can get my UF-1508 over the 1300ish meters I can reach now.

Does anyone know where to buy osram flat black with international shipping?

The Miller, do you know when the flashlight is ready to buy?
The only timeplan I know is: It is done, when it is done. :wink: