This is a good read on the theory of throw, from DrJones:
Thank you all! I just got a lot of info, so have to go study it 
and ofcourse I will post more questions/decisions about it
Thanx!
I found a convoy c8 host, which I like. Is there any quality difference between this and the ultrafire one?
Convoy C8 comes with a textured orange-peel reflector, just what you don't want for maximum throw. It also uses a nonstandard thread for the pill so if you want to use a replacement brass pill to fit a 20mm MCPCB you're out of luck.
20mm MCPCB works much better with the wide base XR-E reflector, no grinding/filing required to clear the wires.
I ment to change the reflector, but if the ultrafire come with the xr-e one, i will just pick that host.
This one is better but out of stock for the moment. About ten bucks more but generally agreed to have better attention to detail and features. They both work fine but if you want to push hard and throw far, generally people talk about the HD2010 as the referrer emcee for how well a light can throw. Draw backs most mention is the challenge of getting the beam dialed in. Either should do you well. Search some of the reviews about the 2 C8’s and the HD2010 to see if one appeals to you more.
XinTD comes with a narrow-base XM-L style reflector. Anything with the XR-E reflector will out throw it, if that's the top priority.
For the reasons comfychair mentioned, I will probably go with the ultrafire hd 2010 just seems bigger or is it just the pic?
Hd2010 is quite a bit bigger. 26650 battery tube, and the head is 17.5mm wider (40%) as well. 2010 is the better light imo, 26650 gives more options and the head size gives more throw.
This is probably the best value for money, if they're ever back in stock. The reflector is plastic, but it's the right shape, the XR-E style. The stock aluminum pill fits a 20mm MCPCB. Also uses a 20mm driver instead of the more common 17mm, but the direct drive BLF drivers are available in 20mm size so if you don't already have one you want to use just buy the 20mm driver. http://www.fasttech.com/products/1618/10002463/1562700-c8-xm-l-diy-led-flashlight-host
The Ultrafire host has an aluminum pill but only fits a 16mm MCPCB, I'm pretty sure it comes with the narrow-base reflector, so you have to get the XR-E reflector separate. Base of the reflector will require mods for clearance otherwise it'll short out the wire solder points. Or, pick up a replacement brass pill that'll fit the 20mm MCPCB, pill also curently out of stock at FT (it's a common part, might be able to find the same thing from a different seller).
UF host: http://www.fasttech.com/p/1562701
XR-E reflector: http://www.fasttech.com/p/1220100
brass C8 pill: http://www.fasttech.com/p/1208600
I have an XRE C8 with a dedomed XPG2. The reflector has a white centering ring that also acts as a bit of a spacer. Would it be better focused without that spacing?
Thank you comfy for the link! That host seems like the one to go with. I was looking for a LED and found this one http://www.fasttech.com/products/0/10001905/1682210-cree-xp-g2-r5-1a-458lm-6500-7000k-led-emitter
would it fit on thebrass pill? Is it suitable for my idea of the light?
The brass DIY pill takes a 20mm star, here: http://www.fasttech.com/p/1682205 But you cannot use that one if you use a hot direct drive driver, it'll fry the LED if it's on a cheap aluminum star like that one. Copper is mandatory at high currents, and even at lower currents you will get more light with the LED on copper. If you can let us know what part of the world you are in it will help suggest where to get parts from. I tried to decipher 'Laibach' and google didn't show anything that looked like a place name.
XPG2 'S2' is brighter at the same drive current than XPG2 'R5'.
So thath one is to weak and I have to look for tje copper base?
laibach is German for Ljubljana, thats in Europe. I think fasttechs shipping is ok for me. Thanx for taking your time!
Would this one be better? One other member recomended it before. But this is just the driver, or does it serve as a base plate to? I mean, can I put in on the brass pill u recommender?
http://intl-outdoor.com/noctigon-xp20-mcpcb-cree-xpg2-s2-2b-led-p-788.html
http://intl-outdoor.com/qlite-reva-71358-multiple-modes-circuit-board-304a-p-710.html
I don't know where to find the empty brass C8 pill, they're out there somewhere though.
The brass C8 pill is sold out for ages at Fasttech, it seems still for sale at lck-led:
But $4.50 for just a pill I think is too much.
For this one it looks like you have to drill new holes when using a 20mm board (if a 20mm board fits at all?)
You are correct - I just checked it now, & the wire holes are spot on for 16mm board, but would require re-drilling for a 20mm board.
In addition, a 20mm board will not fit without reducing the diameter to 19mm.
Well spotted, & a shame it’s not machined properly for a 20mm board.