Please excuse if this is off topic, i was puzzled by the calculation. But after a little study it makes more sense—the lightmeter is calibrated to provide a Lux value for a 1 square meter area at the sensor and not just for the tiny sensor area.
Lux is a measure of the light energy hitting a target area. The units of Lux are lumens/m², where lumens is a measure of the light energy known as luminous flux, with units of cd-sr, candela-steradians. And of course area is measured in square meters.
Steradians are a unitless measure of solid angle, symbol Ω, which is the angle from the apex (light source) subtended by the area of the target.
https://en.wikipedia.org/wiki/Solid_angle
i was assuming the target area was just the tiny sensor area, but it is effectively a 1 square meter target area. So the solid angle Ω subtended at 12.33 meters away is Ω = Area/distance² = 1m²/(12.33m)², or the target Area = Ω ・(12.33m)²/1m²
So to convert: lux = lumens/Area = candela-steradian/ Ω ・(12.33m)²/1m² ;
and solving for candela = lux ・(12.33m)²/1m²
—
Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT
First class build djozz
I had no conception what a Fresnel lens can do until your build. I’m still new here and very impressed how well this works.
Every part of this build is very clean and neat. Great build work djozz
—
Think outside the box too long , cannot find your way back in.
Necessity is the mother of invention and the father is creativity.
Never give up, Never surrender. Make someone Smile today.
I had to finish it today, so here’s the final stretch.
Because the star and the batman projections were not what I wanted for this build, I tried a little spider. The shape was too difficult for the fretsaw, so I went for etching a thin copper sheet, for so long that the copper was eaten through by the FeCl3. I took a long time, and the cutout was not perfect, but the result was rather nice.
Still, this was not the final version. But here are some pictures. Both are at about 40 meters.
Meet the Vir-O-blast C19. My pinstripe is certainly nowhere good enough to apply for a job at RR (link), but I still like my paint job.
The vir-o-blast c19 will not infect you, or cure you from anything (although this post may be the start of a new conspiracy theory ), but it may hopefully brighten up this dark winter a bit
Without the virus stencil in place and with the led die focused, the throw number of this build is over 4Mcd, but with the led die defocused and the stencil focused, the virus projection does 800kcd, still a significant number.
And some pictures of the finished light:
Tonight I will do a small video showing the zooming action, and still some loooooong distance shots showing the 4Mcd need to be made.
You know, somehow I missed this entire entry – lord knows how. It is amazing. Personally I am not going to be happy until I see a BLF logo in that thrower lol! (kidding of course)
fantastic work, well beyond anything i could muster! Good luck!
I love how ‘simple’ it is on the inside! Very clean build.
There is even no driver, the battery is wired directly to the led. I was contemplating building in a fuse for safety but that would cost current, I fear too much.
A sort video from the balcony without the virus stencil to show it is a zoomie. My 10yr son is the camera man so it is shaky, and the focusing of the my phone is a bit lousy but you get an idea. The big trees are at 30 meter, the very end of the square is 125 meter, the square is no match for 4.2 Mcd.
A sort video from the balcony without the virus stencil to show it is a zoomie. My 10yr son is the camera man so it is shaky, and the focusing of the my phone is a bit lousy but you get an idea. The big trees are at 30 meter, the very end of the square is 125 meter, the square is no match for 4.2 Mcd.
.
Great Video , it brings your light to life.
.
—
Think outside the box too long , cannot find your way back in.
Necessity is the mother of invention and the father is creativity.
Never give up, Never surrender. Make someone Smile today.
That zoom function looks very interesting in your video. The different stencils are ingenious. That virus or the spider is going to freak out everyone who sees it.
I liked your build so much that I ordered myself a big fresnel lens. Never imagined what cool things can be done with this. 4.2 Mcd should throw incredibly far.
Please excuse if this is off topic, i was puzzled by the calculation. But after a little study it makes more sense—the lightmeter is calibrated to provide a Lux value for a 1 square meter area at the sensor and not just for the tiny sensor area.
Lux is a measure of the light energy hitting a target area. The units of Lux are lumens/m², where lumens is a measure of the light energy known as luminous flux, with units of cd-sr, candela-steradians. And of course area is measured in square meters.
Steradians are a unitless measure of solid angle, symbol Ω, which is the angle from the apex (light source) subtended by the area of the target. https://en.wikipedia.org/wiki/Solid_angle
i was assuming the target area was just the tiny sensor area, but it is effectively a 1 square meter target area. So the solid angle Ω subtended at 12.33 meters away is Ω = Area/distance² = 1m²/(12.33m)², or the target Area = Ω ・(12.33m)²/1m²
So to convert: lux = lumens/Area = candela-steradian/ Ω ・(12.33m)²/1m² ;
and solving for candela = lux ・(12.33m)²/1m²
Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT
link to djozz tests
No matter how impressive the numbers are – the bat signal trumps everything !!
Great project djozz 
First class build djozz
I had no conception what a Fresnel lens can do until your build. I’m still new here and very impressed how well this works.
Every part of this build is very clean and neat. Great build work djozz
Think outside the box too long , cannot find your way back in.
Necessity is the mother of invention and the father is creativity.
Never give up, Never surrender. Make someone Smile today.
Thanks, there is still little things to be done, like a name and some beamshots, I hope to do them during the Christmas holidays.
link to djozz tests
I like this!
BLF Member Map, add yourself
My 7th Annual contest entry My 6th Annual contest entry My 5th Annual contest entry My 4th Annual contest entry
My DBSAR inspired SRK lantern hand made mod
may I suggest the Dutch thrower?
Or
Throwing Dutchman?
Awesome build!
A box of light
DSS
= Djozz’s Star Shooter
The Flying Dutchman?
Ver licht?
I had to finish it today, so here’s the final stretch.
Because the star and the batman projections were not what I wanted for this build, I tried a little spider. The shape was too difficult for the fretsaw, so I went for etching a thin copper sheet, for so long that the copper was eaten through by the FeCl3. I took a long time, and the cutout was not perfect, but the result was rather nice.
Still, this was not the final version. But here are some pictures. Both are at about 40 meters.
link to djozz tests
I like the spider.
Maybe a slot for interchangable shapes
BLF Member Map, add yourself
My 7th Annual contest entry My 6th Annual contest entry My 5th Annual contest entry My 4th Annual contest entry
My DBSAR inspired SRK lantern hand made mod
That’s AWESOME djozz. If I saw that in real life, I’d be thoroughly creeped out (I hate spiders!)
And now for the finished light!
Meet the Vir-O-blast C19. My pinstripe is certainly nowhere good enough to apply for a job at RR (link), but I still like my paint job.
The vir-o-blast c19 will not infect you, or cure you from anything (although this post may be the start of a new conspiracy theory
), but it may hopefully brighten up this dark winter a bit 
Without the virus stencil in place and with the led die focused, the throw number of this build is over 4Mcd, but with the led die defocused and the stencil focused, the virus projection does 800kcd, still a significant number.
And some pictures of the finished light:
Tonight I will do a small video showing the zooming action, and still some loooooong distance shots showing the 4Mcd need to be made.
link to djozz tests
I love it!
BLF Member Map, add yourself
My 7th Annual contest entry My 6th Annual contest entry My 5th Annual contest entry My 4th Annual contest entry
My DBSAR inspired SRK lantern hand made mod
You know, somehow I missed this entire entry – lord knows how. It is amazing. Personally I am not going to be happy until I see a BLF logo in that thrower lol! (kidding of course)
fantastic work, well beyond anything i could muster! Good luck!
Cool
Regards Xandre
Awesome build, Djozz!
I’m thinking about numerous images to be projected using that flashlight.
Blog: https://lumenzilla.com
I like it !
Haha that little viral addition takes the cake
Looks great!
I love how ‘simple’ it is on the inside! Very clean build.
There is even no driver, the battery is wired directly to the led. I was contemplating building in a fuse for safety but that would cost current, I fear too much.
link to djozz tests
Fantastic build
A sort video from the balcony without the virus stencil to show it is a zoomie. My 10yr son is the camera man so it is shaky, and the focusing of the my phone is a bit lousy but you get an idea. The big trees are at 30 meter, the very end of the square is 125 meter, the square is no match for 4.2 Mcd.
link to djozz tests
I bet he’s proud of his Dad!
Well, he already takes his dad’s weird hobby with a grain of salt I’m afraid, no unreserved admiration
link to djozz tests
.
Great Video
.
Think outside the box too long , cannot find your way back in.
Necessity is the mother of invention and the father is creativity.
Never give up, Never surrender. Make someone Smile today.
Uau, I hadn’t seen the final version, this is uber cool
Liked the name of the build too! Beware, you foolish virus
Well done
MY REVIEWS THREAD /// My Flashlight Collection ///
Mods: 1 / 2 // TIR: 1 / 2 // Others: Biscotti 3 + 1*7135 / Triple TIR w/ XP-G2 /// My Review's Blog (PT) /// OL Contest 2019 /// OL Contest 2020 /// GIVEAWAYs: 1 / 2
Cool
What about rubber feet to not scratch the bottom?
And a a handlebar mount for the bicycle ?
So that you can light up where you are going to be in five minutes time
link to djozz tests
Very well done, djozz. Awesome build and finish.
That zoom function looks very interesting in your video. The different stencils are ingenious. That virus or the spider is going to freak out everyone who sees it.
I liked your build so much that I ordered myself a big fresnel lens. Never imagined what cool things can be done with this. 4.2 Mcd should throw incredibly far.
My Youtube channel: Alllightson Reviews
My 7th Old lumens contest build: Matainvoy ML18S, Built video
My reviews: Sofirn SP31 V2, Nightwatch NI40, Sofirn C8F 21700, Brinyte WT01, Sofirn SD05,Ti AAA keychain, Sofirn SP33 V3, Skilhunt M150
My Youtube video-reviews: Brinyte WT01, Sofirn SD05, Ti AAA keychain, Sofirn SP33 V3
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