When you make a LED reflector light with such extreme focus, there are some unusual side effects. Many of you have probably noticed that most lights produce a slight donut hole when you hold them close to something.
Well, this light still produces a donut hole in 3m (9.8ft) distance!
You can see this on some of the beamshots, the beam looks “hollow” for the first few meters.
Here is a realistic white wall shot of the hotspot in 2m (6.6ft) distance:
Since you can’t see the corona in that shot here is another one with higher exposure (corona ist now realistic, the hotspot itself is overexposed):
The reason for this is the same as for the minimum distance where one can measure accurate candela values.
What a gun :exclamation: :smiling_imp:
Congrats for building up this fantastic record breaking construction.
You really make it guys.
The only thing I would like to disagree with, is that this flashlight should be “completely useless though, the spot is way too small to find anything. laughing But then again that was never our intention. The only remaining application: cloud bounce! <img src= ” /> ”.
IMO this light is extremely sensible and very useful flashlight, as cloud bouncing and even spotting a small point of light on other far away objects are some of the really important themes in context with a lot of serious science, at least in modern physics. :student:
Not to forget the infinite eternal wisdom comments on the General Spot Size Factor Theories, that one of my grand-grandvathers used to proclaime while he had to manage a totally unexpected stormy, slippery and curvey late night sidewalk, caused by just one beer too much. But after some decades of nothing but hard work, he came up with his theoretical essence, which is a brilliant piece of mindbreaking cosmic beauty. :innocent:
The fundamentel law is genious and even simple.
As long as the spot size is big enough to enlite the key hole area of my castles front door, there is absolute no problem!
There was a thread where a BLFer spoke about using simple plexiglass
He measured better light pass through then his AR coated glass and a stock lens.
I don’t know who or where but maybe somebody else does for it was met with some disbelief so he posted his exact measurements.
In this case maybe a little less good lens without that light blocking center would be just the same but better looking and much easier to replace (make a new) and cheaper.
Wow that guy is just barely over the lux you got with the single reflector…
With some better cooling and driving the LED harder you could pass 1.6Mcd
My Black Flat LED is being driven at 6A for max output.
Do you have a link to a forum thread or something about the Scheinwerfer?
I hear a lot of talk about it but have never seen any first-hand information about it, just claims of 3M cd which seems inaccurate.
About the throw record, I guess it depends on your definition of “portable”. Large fresnel lenses make it pretty easy to get huge throw numbers, but the beam is not so nice. What did you mod today? - #1519 by EasyB
Edit: of course the design and execution make a big difference to the usability of the light. For example my light in the link above I put together in an hour or so, but it’s flimsy and not so nice to use.
True, you can always just add a bigger lens and get a bigger number…
I guess we should be sorting these lights by category, like best thrower with <=150mm head, best thrower with <=100mm head, and stuff like that.
The_Driver’s searchlight here definitely wins in the sub-150mm reflector category
Did not read the entire post yet, just quick reading, but man, what a cool project, must have cost you some energy, but the result is astonishing !
Very nice
- we would need every detail about his setup (what lens, what lux meter, how the setup looked etc. etc.)
- cheap ar-coated lenses from China often just have 96 percent transmission (uncoated normal glass has 92 percent, borosilicate has 94 percent)
UCLp lenses from flashlight lens (ar-coated acryllic lens) have 97 percent
- high quality ar coated glass lenses can have upwards of 99.5 percent (camera lenses for example)
During optical measurements it is almost impossible to get a tolerance under 10%. So it’s very difficult to do reliable measurements.
I can tell you: the difference between a UCLp and a normal uncoated lens can be seen with the naked eye when looking at a reflector. It looks much “shinier”.
Blocking the center of the lens only impacts the spill, this is because it is only blocking the direct light from the emitter as compared to the collimated light from the reflector. So that disc in the center is hurting nothing at all.
Yes everything that is AR coated looks shinier…
If plastic(plexiglass,acrylic) works than it is worth a try cause they are dirt cheap.
Yes F1.2 camera lenses should have great light transmittance but they have special AR coatings that don’t go with flashlights. How do I know?
I have build aspherical flashlight(and IR illuminator) out of high quality Yukon 3x42 F1.2 lenses (triple lens system) and while it had ultra clear die projection(clearest projection I ever seen even clearer than B158) it seems that AR coatings on that lenses disables light transmittance(probably by not letting out blue color of emitter) resulting in poor kcd performance.
So maybe just maybe AR coating at some lenses is not that good as we expect.
There are different types of AR coatings.
For best performance it needs to be a VIS coating, if it is meant for IR or UV it will negatively affect performance in the visible light range (which is what flashlights make).
I’m not sure how you compared your lenses, did you buy some that had AR and some that didn’t?
An AR coated lens will always outperform a non-AR coated one if it is the correct type of coating.