I'm sure you know the answer to your own question but wont answer it here due to repercussions. Either that or your to polite. 
I read what is going on here but dont understand a lot so dont respond. The same in a lot of technical threads. Keep up the good work guys.
That's clearly die WalkĆ¼re von Wagner!, what else? :bigsmile:
This is pretty awesome.
For the next one, you going to use the Fresnel from an old big screen TV?
Like MRsDNF said: I read everything in this thread with great interest but I do not understand āsomeā of it.
āsomeā being quite a lot, actually. 
If I cannot add anything usefull, I do rather not post at all.
Grtz
Nico
Same here, i subscribe to interesting threads like this but if i canāt add anything of value i often donāt post.
But i have to say good work djozz 
It looks great both the beam & box.
I wish i had the willpower to keep modding when the world is so beautiful outside :bigsmile: but i havenāt modded a single light since may, It is just too bright & nice outside in summer here, and so few dark hours at night i hardly get to use them at all 
I canāt wait until the darker months so i can find time to mod again
In that case: use the long summer days to be prepared for the long winter nights!
Grtz
Nico
Makes perfect sense, go modding when the light's out. Looking forward to the new batch this winter :-)
About me saying 'smart' things, as a biologist and not into physics I only know some basic optics (unlike a few here on BLF who are way more knowledgable than me), but I'm fairly good in thinking those basics through and find a practical use for it in this hobby. And I can not help myself boring the BLF community with that. (As long as it comes with beamshots I think I can get away with that ;-) )
Now now Djozz, no fals modesty please
I personally think you are one of the members truly contributing to this foruym so pls keep it up!
Grtz
Nico
Djozz, I think you have a lot more fans than you think. Like others have said, sometimes I very much enjoy a post, but fail to comment. Usually because I canāt think of something constructive (or witty) to say ā other than maybe the overused āawesome.ā
Soā¦ā¦. āAwesomeā, it is.
Oh wait. I just thought of something almost constructive. Did you know almost everybody mispronounces āFresnelā?
(at least here, in the backcountry.)
āAugustin-Jean Fresnel (French pronunciation: [ÉgystÉĢ ŹÉĢ fŹÉnÉl]; pronounced freÉŖĖnÉl fray-NELL in English) (10 May 1788 ā 14 July 1827), was a French physicist who contributed significantly to the establishment of the theory of wave optics. Fresnel studied the behaviour of light both theoretically and experimentally.ā
BTW he was born at Broglie. Not many french people know how to pronounce correctly āBroglieā
Two outside beamshots in this thread:
Saw that thread! Wow! :cowboy_hat_face:
I did not seen this thread before. This is very nice experiment with extreme kcd numbers and very nice rainbow beam :)
Wow!
Why was I snoozing on this thread? My perspective on making throwers or search lights completely changed upon reading this. I have to admit though that there are a lot of things I donāt understand also. 
I think Iāll copy this concept shamelessly when I try to build a āportableā ultra long range search light for our rescue team. :bigsmile:
A few tips: measure the focal length of the lens carefully, at a distance as large as possible, and then very carefully make the box with the corect dimensions. My box allows a focal correction of a cm, but that appeared only just enough, more focal travel than that is not a luxury. I was surprised about the focal difference between 20 meter and infinity. Mount the lens as flat as possible (a rigid frame) and stress-free. The finning on the back appeared completely unneccessary for an XM-L2 at 5A.
Does it have a moonlight mode and does it come with a pocket clip?
Thank you for the tips djozz! I will keep that in mind.
I am going to build something like this with an CXB3590 @140 watts
though I need a collimator lens right in front of the COB to narrow the spread of it, I got a 90mm diameter and 90mm focal length lens so far but that is not enough, I will need a near (half)sphere to get a narrow enough beam of the COB for my fresnel.
I see, so you are going for maximum output in your build. I have asked myself that, more light is more useful but smaller light sources (less light) give a more intense hotspot. Iām still debating if I should rebuild the light with a Cree XHP70.2 for more light and still a pretty intense hotspot.
the collimator should compensate for the die size, it would make it look like a 3x3 mm LED from the focal point of the fresnel, which is pretty small, given lens loses and spill there should still be >60% of the LEDs light remaining.
I was also thinking about using a fresnel mirror to narrow the COBā¦