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

Yes will update list later

Well as with the Q8 it was agreed upon a low groupbuy price and afterwards the manufacturer can set own price

Congratulations Sky :). You are now, without doubt, getting a GT!

So basically, now that more than 555 1st lights have been claimed, the 2nd and 3rd (+etc) lights will all be at a set msrp?

I guess I was asking if there was a chance there would be a second groupbuy.

I am sure that the number was set at 555 because LT in not making much on those lights and they want to sell some at a higher profit. My guess is that BLF might be able to put together a second group buy at a lower price than Lumentop ends up selling them for in the future, but I am sure they want to sell some on their own first. Just a guess though, I have no inside info.

No, not all of the 555 people will end up buying them.
The other people who are adding their name even though they’re higher than 555 will be moved into the empty slots to fill the 555.
So it’s almost certain that all 555 slots will be filled by individuals, and if you wanted 2 or more lights you will only get one from the group buy and need to wait for Lumintop to bring them to retail at regular price, then buy the rest yourself.

It is still possible that a ton of people bail from the 555 and there aren’t enough other people to fill the slots, then second and thirds will be handed out to people who asked.
.
PS- someone in another thread though I was on the list for the GT? lol :stuck_out_tongue: I just joined the thread at the beginning to do all the reflector calculations because I wanted to help out.

Since we now have a precise looking drawing with the dimensions of the reflector, I will calculate the throw:

Luminous_intensity[cd] = luminance_LED[cd/mm^2] * area_of _reflector_as_seen_from_hotspot[mm^2] * reflectivity_of_reflector[%] * transmission_of_lens[%]

Inner diameter large opening: 120mm

Inner diameter small opening: 5.9mm

Area of reflector as seen from hotspot: 11310mm2 - 27mm2 = 11283mm2

Luminance of XHP-35 HI E2 @2.5A: 136cd/mm2 (source)

Reflectivity of aluminium reflector: 90%

Transimission of uncoated glass lens: 92%

Maximum possible luminous intensity (throw): 1,271kcd = 1.27Mcd

Now a few caveats:

  • this calculation assumes a perfectly precise reflector and a perfectly positioned LED
  • there is also always some uncertainty with sma's measurements (+/-6% because of LED Bin, +/5-10% because of Lux meter etc.)

EDIT:

this pic seems weird:

The guy must have dinner plate sized hands to make it look that small. I know because I just had a light built with an 118mm reflector. It's rather large.

So probably around 2km throw in reality?

Well yes, a little bit more actually.
1,000kcd = 2km ANSI range

Well idk about after the groupbuy we will have to see.

1,27Mcd sounds good :smiley:

That pic should be oriented 90° and I think the hand is more pointing to it coming in from the cam, not holding it.

Can you calculate the area of the TN42, and then based on the Kcd of the TN42 calculate what the Kcd would be for the GT?
Just to see how close the value is to the 1.27Mcd.
Always good to calculate stuff in more than one way.

So it’s pretty much an alien death ray. Cool. The heck with using a “disabling strobe” for muggers! :smiley:

Yes, of course (you know the formula and I just edited into my above post for reference). All you need are the inner diameters of the reflector openings (or at least the large one). There is some uncertainty though because you don’t know how good the AR-coating on their lenses is (I would calculate with 96% transmission rate).

:smiley:

Yeah I was just asking you to do it so I didn’t have to look up the measurements :stuck_out_tongue:
Anyway, I’ll do it, here is the area of the TN42: 5961
GT: 11283
TN42 lux: 728Kcd

GT lux:
11283 / 5961* 728 = 1.38Mcd

Very close to the value you got :slight_smile:
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EDIT- looking back on this, I realize I made a mistake and forgot to remove the area at the middle of the GT’s reflector.
It is not 11283, it is actually 10500mm^2
This gives 1.28Mcd which is almost exactly the same as what The_Driver got.
My bad.
This does match what the GT is getting in tests :slight_smile:

What Bin do they use in TN42 (also what current was the LED running at? the number seems a bit high, was it modded?)? This could explain most of the difference.

EDIT:
Did you ignore the different transmission rates of the lenses? I got 1.32Mcd,

Cool white: Review: ThruNite TN42 LED Searchlight | Candle Power Flashlight Forum
All tests I’ve seen show it to be above 700Kcd, much higher than the manufacturer rating.

I think I might have been misunderstood; I was trying to say I’m going to buy this light anyway I can regardless but if I can get in on the OG run because of no-shows for $111 and save some money that’d be even better. I wasn’t trying to say it was too expensive. I’d buy it even if it was $200.

No it is good to clarify things every now and then in these larger topics.
:wink:

Says plastic lens in first post and not glass…

Assume that has diffrent transmission rate?

Depends on the type of glass and type of material. Generally there is not much of a difference.