Being able to hit a 1200m target with 0.25lux at that distance needs 360kcd.
If it is 0.1lux at that distance your light only needs to be 144kcd, which makes more sense to me.
Did you use a binoculars or similar thing to observe the target?
No, i observed it only with bare eye, adjusted to darkness.
The target was a large unfinished building, see the attached pictures.
I do not know at what lux a target needs to be hit with, to be able to see it with the naked eye.
Where can i find the Kcd to meters calculator ?
According to flashlightwiki, at the same current XP-G2 gives more lumens than XP-E2, and they are both good throwers.
What is IOS?
*i*ntl*o*utdoor *s*tore
No way XP-e2 can throw 200KCD in UF T2(you can be happy if it will throw little above 120K)... Well maybe with ahorton aspheric lenses but I did not try that...
Second I have premium flashlights like Xsearcher tuned with real 450KCD(my avatar picture) and although it can throw more than 1000 meters I don't think it has useful throw on more than 800.
My tuned nightmaster throws 250 KCD and no way it can reach 1200 meters... Useful light up to 600 meters
Sure you see reflection from high reflective surface like white buildings/objects/traffic signs which acts like mirror collecting rest of distant light from your flashlight... But try to do that in a real nature on tree which is 1200 meter away so you will see it will not reach it...
Get yourself a light meter for approximate readings.
Very small surface brightness difference between XP-G2 and XP-E2 & sometimes real hand selected XP-G2 beats the hell out of "average" XP-E2.
My verdict is XP-G2 for medium to big aspherics, and XP-E2(I tried this in everything including reflector flashlights) for very small aspherics like sipik clones.
Candela to throw conversion here: http://flashlightwiki.com/Light_Output_Measurements
Based on this, 200 kcd is 894 meters to get 1/4 lux which is roughly the light of a full moon.
I agree with bibihang - maybe you are seeing about 0.1 lux hitting the building, and this puts it in to a better perspective. Eyeballing things is very deceiving to use, unless comparing lights of course...
luminarium iaculator,
Yes, i should get a lux meter, but for now it has to wait.
First i have to finish my next thrower project, I want to break the 1 milion candela with a XP-E2, a 80mm aspheric lens and a recycling light collar.
I do not care if it will be a pencil beam, I bet that at 500+ meters, the hotspot will be large enough to fully illuminate a person or animal.
Until then, more throw tests on the field 
At 1200m the throw is not useful whatever light you have, if you don`t use some sort of optical system.
My target building color was gray, unfinished concrete. Yes, it is a brighter color, but i do not consider it to be high reflective.
Yes, the trees are known to “absorb” the light and are much harder to hit, I did not even think to try it.
In my first test after modding the uf t20, different location, I was able to see a building being hit at 700m even on medium power(1,2A tailcap current).
The fun part is that after playing with the uf t20, I started my other thrower, a Trustfire TR-J19, dedomed noctigons XM-L2 U2 1A, 4,6A tailcap current(3x 32650 6Ah protected trustfires) and it was appearing like a freaking flood light in comparison with the aspheric :). Of course the moded J19 throws more, but besides the hotspot it has quite a bit of flood and the atmosphere is more strongly illuminated.
I am glad that you like thrower flashlights Borg,
I like them very much but XP-E2 is not something you want to use in Big Aspheric like Xsearcher or Crelant except for pure fun. If it is for fun observation 500+ meters than it is ok. You decide.
80 mm aspheric(assuming it is high quality lenses) in combination with hand selected XP-E2(driven up to 3A) will give you around 500 KCD, and XP-G2 has better performance when overdriven (more than 4A)than XP-E2 for which probably does not have any sense to go over 3A because it will start to loose performance?
You can try and convince yourself on harder way... Make both pills(XP-E2 and XP-G2) so you will see what I am talking about. Good luck with modding.
Yes ! High power throwers are great
I will test both, the XP-E2 and and XP-G2 in the 80mm aspheric.
Do you have any experience with different heights of the same diameter aspheric lens?
What effect on the beam will have a higher lens, assuming that both lens have the same focal length and they are the same diameter ?
By height you mean thickness? The diameter, focal length and refractive index determine the curvature and therefore most of the thickness of a plano-convex aspheric single step lens, the other free parameter being the thickness at the outside edges.
the normal pill from the c8 go in to the TF 20?
Where to buy copper pills this time?
there are not on fasttech and wallbuys
Fritz t. Cat, yes, thickness.
I need to choose between 2 lenses :
One has Outer diameter: 78mm, inner diameter: 71,1mm, thickness : 30.5mm and focal length : 50 mm
One has Outer diameter: 80mm, inner diameter: 72mm, thickness : 38.7mm and focal length : 52 mm
Both being almost the same focal length and inner diameter, they can catch the same amount of light. But The 80mm one is 8mm thicker. What difference for the hotspot will this make ?
I need the one that can provide the best throw.
Good luck in finding quality lenses for your project because you will need it 
Order both of them... There is no universal advice here...
In may past I ordered about 5 big lenses with different focal points, from different vendors and I was not to happy with them. They are mostly blurry and unusable to me. They can not match quality of dereelight lenses...
My advice to you is to try car optics... I did not tried but plenty of guys did good aspherics with them.
Here is focal difference in 2(left Tiablo right Dereelight) high quality lenses (Dereelight gives slightly better performance but you will need to set up emitter closer or higher depending which type you will use)
So order plenty of them from different vendors and good luck
Unless it is just the thickness at the edge, the only reason I can think of that two lenses with nearly the same diameter and focal length would have different thicknesses is that the materials may have different refractive indices. The strength of a lens is the refractive index times the curvature. I don’t see that that affects the throw.
i think i got t20 with 10 days….is it one aluminum pill or brass/copper pill inside ?
Mine is brass pill. If it appears as yellow colour then it is brass.
Please don't be mad but I can not read this even with google translator. My English is poor. Could you simplify this on basic English?
A lens works by making all the path lengths from the focal point to the output beam the same optical length. That is, thinking of light as Isac Newton’s particles, the ones with geometrically shorter paths near the center are slowed by the plastic or glass of the lens so that they arrive in the beam at the same time as those going out at the edges of the lens. A focus is caused by many ray paths being equal in phase so that the wave interference is constructive. Or an other way to look at it is that rays leaving the source at different angles are focused to the same angle by the angle at which they leave the lens or mirror. So the strength of a lens depends on how much it slows the center rays, relative to the outer rays. That is equal to the refractive index of the lens material times the difference in path lengths through the material.
Hope this helps.
Fritz t. Cat,
You are master of physical science... Or at least physic professor?
I can only be your assistant in physic(passing something to you while you doing research or something).
But I think I understood something. Thanks
Thanks.
Maxwell’s equations of electricity and magnetism are the thing of which I am the very surest. I might be crazy and not really be at home or on my computer or who I think I am, but I know I am not ignorant.