# SST-50 homemade spotlight



## EasyB (Jul 8, 2010)

Hi everyone, I have just now joined the forums but they have been a source of knowledge and inspiration in the past. I became sort of obsessed with building this LED thrower. 











A short focal length lens collects most of the light from the LED and the large fresnel lens focuses it far away. The LED is actually inside the focal length of the small lens, creating a virtual image that the large lens sees. The large fresnel lens is 13" in diameter.






The power source is two 18650 Li-ion batteries on the backside. The voltage is regulated and adjustable by turning the blue potentiometer. The voltage regulator is one made by fujitsu that I got from mouser.com. Its max output current is 8A.






Further away, the LED appears to fill the entire lens.














That tower is about 250 meters away. The current was about 5A in these pictures. I don't really have a good spot nearby to do beamshots, but I was able to illuminate a tower about 900 meters away before. 

Thanks for looking.


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## DM51 (Jul 8, 2010)

*WOW!!* Welcome to CPF, EasyB  !!

That is a spectacular first post - what a superb light! Brace yourself for a lot of questions and comments from admiring members!


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## ninemm (Jul 8, 2010)

DM51 said:


> *WOW!!* Welcome to CPF, EasyB  !!
> 
> That is a spectacular first post - what a superb light! Brace yourself for a lot of questions and comments from admiring members!



Yep, what he said!  Welcome and awesome job. Very unique and the quality of the build looks great.


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## John_Galt (Jul 8, 2010)

Super nice light, man!

Two things: What kind of 18650's are they? For such a high current drain, I would suggest a couple of AW brand IMR 18650's. They have noticeably lower capacity compared to some other cells out there, but they are able to be safely discharged at ridiculously high rates, with minimal voltage drop.

The other thing is more heatsinking. This is probably a short-time only thing, but to ensure maximum output for a long period, I would suggest finding another mounting point for the batteries, and putting a large CPU finned heat-sink on the back of that chunk of aluminum. 

But again, very nice!


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## Linger (Jul 8, 2010)

Sick.
Excellent beam-shots.
Thank-you.


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## EasyB (Jul 8, 2010)

John_Galt said:


> Super nice light, man!
> 
> Two things: What kind of 18650's are they? For such a high current drain, I would suggest a couple of AW brand IMR 18650's. They have noticeably lower capacity compared to some other cells out there, but they are able to be safely discharged at ridiculously high rates, with minimal voltage drop.
> 
> ...



Thanks for the suggestions; you're right it is kind of a short term novelty light right now. It's a fairly sizable chunk of aluminum; after it being on for several minutes the metal was slightly warm to the touch. 

I checked the battery voltage the other day and it was 3.93V per cell open circuit, 3.81V full power. They are Tenergy 2600 mAh cells from batteryjunction.


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## mrartillery (Jul 8, 2010)

Nice light! :huh: And BTW +1 on excellent first post!


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## gt40 (Jul 8, 2010)

Great effort! Could you share more on the specific voltage regulator you used?


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## JamisonM (Jul 8, 2010)

Bookmarked. I can't wait to see what it can do when it's really tested!


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## EasyB (Jul 8, 2010)

gt40 said:


> Great effort! Could you share more on the specific voltage regulator you used?



Sure, here is the product page:
http://www.mouser.com/ProductDetail/Fujitsu/FPMR12TR7508PA/?qs=ESP0OwbMTIA5u7FiiObSlA==

The voltage specs are there. The output voltage is adjusted by changing the resistance between two contacts on the regulator. You can see it in the electronics closeup pic above. It's at the bottom right; about 3x1cm. The output voltage doesn't change when the load changes, which is a nice feature.


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## kingofwylietx (Jul 8, 2010)

Very impressive first post. 

That's a very cool spotlight....I like the skeletonized look.


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## daytec (Jul 8, 2010)

very nice , where did you source the lenses............marty


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## js-lots (Jul 8, 2010)

That is awesome, I cant wait to see what kind of edc's you start to make.


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## Linger (Jul 8, 2010)

js-lots said:


> cant wait to see what kind of edc's you start to make.


Is that a fresnel in your pocket or are you just happy to edc?


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## SmurfTacular (Jul 8, 2010)

+1  What an amazing dual lens design you got there! Great solution for all the dead light usually produced by normal fisheye flashlights

Where did you get those lens's!?


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## Th232 (Jul 8, 2010)

Very nice work.:thumbsup:

:welcome:


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## Hack On Wheels (Jul 9, 2010)

Wow, I'll have to echo the others in saying that was an amazing first post! 

It makes me want to try a dual optic Maglite mod... with something smaller like an XR-E or XP-E. I'd have no idea where to start though!


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## EasyB (Jul 9, 2010)

Whoops I thought I mentioned this in the post; the lenses are from edmund optics. You can get somewhere a 4'x3' fresnel lens used in projection TVs. That would make a spotlight a bit less portable than mine, but it would shine something powerful.


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## ^Gurthang (Jul 9, 2010)

Easy,

Welcome and a tip 'o the hat for your project. Love the "light saber" pic, sorta like the Martian's heat ray from War of the Worlds  all you need to add is the hissing sound....


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## kramer5150 (Jul 9, 2010)

oh Lordy!!! I just soiled my boxers @ that beamshot.

Awesome work, very impressed with your fabrication skills.:thumbsup:

Curious...
How come so much light is being spilled out to the immediate sides? The light thats illuminating you as you hold it... where is that light coming from? Is it being reflected back at you off the lens surfaces?


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## saltytri (Jul 9, 2010)

Holy Smokes, that is way beyond cool! Thanks for posting this - it is unusually interesting. :twothumbs


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## Al Combs (Jul 9, 2010)

Wow. Really impressive first post. Nice work.:twothumbs

and

:welcome:


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## wquiles (Jul 9, 2010)

Great project


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## Al Combs (Jul 10, 2010)

I'm not sure if this is something you've already considered in your regulator setup. But here is a good thread discussing a potential problem using a voltage regulator instead of a constant current regulator with an LED. Luminus says the SST-50's Vf temperature coefficient is -4.4 mV/ºC @ 1.75 amps. I'm guessing that value goes up at higher current levels. KillingTime mentions in post #3 of that thread after a 30 minute runtime test, the Vf of his SST-50 had dropped enough to trigger his regulator's hiccup mode for short circuit protection at 10 amps. In post #19, pepko describes his use of a thermistor to compensate for the LED's drop in forward voltage. I don't know if he set that up by trial and error or what. Of course the best would be a good constant current regulator.


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## EasyB (Jul 10, 2010)

kramer5150 said:


> oh Lordy!!! I just soiled my boxers @ that beamshot.
> 
> Awesome work, very impressed with your fabrication skills.:thumbsup:
> 
> ...



Yes, I think it's just from the light that's peeking around the collection lens and from scattering off the lens surfaces. Gives you an idea of the significant amount of light lost upon going through lenses.

Al Combs, I did consider the problem of current runaway, but I don't have a great solution, I just set the voltage so I have a bit of room for current increase and I think it's pretty well heat sinked, just what the original poster of that thread did. I monitored the current for few minutes and it was fairly stable.


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## vestureofblood (Jul 10, 2010)

Wow!! Very unique, that was more than I was expecting when I walked into this thread. Great job.


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## aurum (Jul 11, 2010)

Hmm ... I don't see any pictures


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## scott2907 (Jul 11, 2010)

No pictures!! Help I need to see this!!!
:mecry:


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## bansuri (Jul 11, 2010)

aurum said:


> Hmm ... I don't see any pictures



Same here, I'm starting to wonder if all the other posts are tongue-in-cheek?


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## EasyB (Jul 11, 2010)

Sorry everyone who hasn't seen the pics, you are really missing out. 

I was hosting the pics on some space provided to me by my school, but the whole system seems to be down right now. I'll put them somewhere else if I need to, but I hope they will be back up sometime soon.


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## Walterk (Jul 11, 2010)

omg.... 330mm diameter.....!!
missed that part earlier.


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## Vbeez (Jul 11, 2010)

Interesting indeed


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## DM51 (Jul 12, 2010)

EasyB said:


> Sorry everyone who hasn't seen the pics, you are really missing out.
> 
> I was hosting the pics on some space provided to me by my school, but the whole system seems to be down right now. I'll put them somewhere else if I need to, but I hope they will be back up sometime soon.


You might want to consider a proper hosting site such photobucket.com (or equivalent) for your photos. It is important to CPF that images will be available long into the future, so people returning to threads for reference can still see them. Your school is not likely to want to host your images after you have left, and its server has already proved less than reliable anyway.


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## download (Jul 12, 2010)

Wondeful mod!!! :welcome:


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## Walterk (Jul 12, 2010)

Great and clear pics! Like the build.
Makes sense to use a sst50 instead of the much favoured XRE to have a strong spot.


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## Illum (Jul 12, 2010)

any word on selling DIY reflectorless throwers in the future? or at minimum build plans and material recommendations?


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## jspeybro (Jul 13, 2010)

oo::huh: nice!



EasyB said:


> A short focal length lens collects most of the light from the LED and the large fresnel lens focuses it far away. The LED is actually inside the focal length of the small lens, creating a virtual image that the large lens sees. The large fresnel lens is 13" in diameter.



Did you just get the lenses and then put them together to get it in focus, or did you calculate it specifically and then source lenses? or both, caclulate for available lenses?

By putting the LED slightly further away from the first lens, you could probably reduce the size of the second lens at the cost of less collected light. Also a shorter focal length of the second lens could reduce the size even without changing the position of the first lens, but usually large lenses with short focal lengths are not very common.

If you're using lenses from Edmund Optics, your getting quality lenses (which have a price of cource), but the result is just great.

This actually looks much like something I'm going to do with a Luxim light emitting plasma light in the near future (still waiting for the light to arrive).

Johan

EDIT: would you care to share a picture taken from the side and of the total setup when the light is on (maybe dim it a bit not to overexpose the camera) so we can see the light path between the optics?


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## Walterk (Jul 13, 2010)

Side mug shot would be interesting indeed!
Ask someone to blow some smoke in the area to make it easier to capture on film...


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## EasyB (Jul 13, 2010)

jspeybro said:


> oo::huh: nice!
> 
> 
> 
> ...



I actually went through anchor optics, which is connected with edmund optics somehow. The lenses were fairly inexpensive compared to what you'd get at edmund optics. I don't think I had this exact design in mind when I purchased the lenses. Got a bit lucky I guess. I picked the small lens because it has a very high diameter:focal length ratio. 47mm diameter, 21mm focal length. I picked the fresnel lens because it's big and round.

I'll try and get a good side shot with the beam on.


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## JonN06 (Jul 13, 2010)

That is super cool. I need to learn how to do this stuff. Thanks for showing it off. :thumbsup:


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## jirik_cz (Jul 13, 2010)

Simple and extreme  Just wondering how much lux this could have. 500k? :thinking:


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## jspeybro (Jul 13, 2010)

EasyB said:


> I actually went through anchor optics, which is connected with edmund optics somehow. The lenses were fairly inexpensive compared to what you'd get at edmund optics.



yeah, edmund is like thorlabs and newport, just making sure they can provide you with anything optics related, hide where they get it it so people think its all edmund thorlabs or newport. in many cases they buy the smaller companies, but sometimes, the companies still exist and they are just distributors.

smoke would be nice :ironic:


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## ostrograd (Jul 13, 2010)

Fantastic! Using a two-lens optical system is a great idea. It's a bit like the Dedolight optics, which I've always thought would be an interesting avenue to explore for portable lighting and possibly flashlights.

Their website's a bit weak, but nevertheless has some worthwhile information on the design (look under Optical System, Lenses, and Mechanics). They're used mostly in film and video lighting.

I have a few and much prefer them to standard fresnels; the design really is miles better. And they have incredible throw.
Seems there ought to be some good ideas in there for other lights...


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## Walterk (Jul 14, 2010)

ostrograd said:


> Dedolight optics, Mechanics...


Awesome! Try the animation.

And in the beamshots in the first post you see how the beam needs distance to mature. 
@EasyB: In the shot lighting the tower, it seems the narrowest part of the beam is not at the tower but somewhere inbetween. Is that true or is that only apparantly?


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## haode (Jul 14, 2010)

Nice light !  Haha ever thought of making a casing for it ?


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## MikeAusC (Jul 14, 2010)

Walterk said:


> @EasyB: In the shot lighting the tower, it seems the narrowest part of the beam is not at the tower but somewhere inbetween. Is that true or is that only apparantly?


 
Yes, it had me wondering too ?


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## jspeybro (Jul 14, 2010)

maybe the large lens is slightly too far away causing it to focus rather than to collimate.


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## Hack On Wheels (Jul 14, 2010)

Would anyone here be interested in doing a how-to on the calculations for designing a two-optic system like this? With the little I've learned about optics, I wouldn't feel confident trying to figure it out myself.

This really is the most interesting project (to me) that I've seen on here in a while; it's such a different approach and looks to result in a very nice beam.


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## scott2907 (Jul 14, 2010)

Pictures are back on !!!!

WOW THAT THING IS FANTASTIC!!!!!

Well done mate, I wish I had your patience/creativity.

Nice one :twothumbs


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## Walterk (Jul 14, 2010)

Hack On Wheels said:


> Would anyone here be interested in doing a how-to on the calculations for designing a two-optic system like this?



More about the functioning of the pre-colimator can be found in the thread *Formula for calculating throw using aspheric lens *.

Making calculations seems to be quite hard, and seems to be a matter of trial and error. From my experiments a f-0.55 first lens, and a f-2.0 large lens works best with the f-2.0 lens.
Other combinations might work better, but I can't tell, as a layman myself.
You might google for 'beam-expander', as that is a common application of this principle.


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## jspeybro (Jul 14, 2010)

Hack On Wheels said:


> Would anyone here be interested in doing a how-to on the calculations for designing a two-optic system like this? With the little I've learned about optics, I wouldn't feel confident trying to figure it out myself.
> 
> This really is the most interesting project (to me) that I've seen on here in a while; it's such a different approach and looks to result in a very nice beam.



I could, but don't have all the necessary details for this setup. I'm in a hurry now so maybe I find time somewhere this week to explain the setup.


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## Armed_Forces (Jul 14, 2010)

DM51 said:


> *WOW!!* Welcome to CPF, EasyB  !!
> 
> That is a spectacular first post - what a superb light! Brace yourself for a lot of questions and comments from admiring members!





*Spectacular indeed!* 

Members such as EasyB are what make this forum so special. 
I gladly contribute to help with expenses here for this very reason. Everything else is just gravy. 
Thanks for joining/posting EasyB !!

:welcome:


lovecpf


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## COAST (Jul 14, 2010)

DANG!!! Nice thrower!!!


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## EasyB (Jul 14, 2010)

Thanks for all the compliments; I'm glad you guys like it. 

About the focus of the beam, it's possible it could be improved, but not by much.

I'm excited about my next light project. I'm going to stick a 55 watt HID in an $8 spotlight I got from walmart. Its reflector is 85mm in diameter. The HID kit is going to be from DDM tuning. It will be powered by 4 A123 brand LiFePO4 26650 cells. It won't be quite as unique as this spotlight, but sometimes I'm just power hungry.:rock: I'll definitely show it off here when I'm done.


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## EasyB (Jul 14, 2010)

Here is the requested smoke shot to reveal the beam between the lenses.


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## Hack On Wheels (Jul 14, 2010)

Walterk said:


> More about the functioning of the pre-colimator can be found in the thread *Formula for calculating throw using aspheric lens *.
> 
> Making calculations seems to be quite hard, and seems to be a matter of trial and error. From my experiments a f-0.55 first lens, and a f-2.0 large lens works best with the f-2.0 lens.
> Other combinations might work better, but I can't tell, as a layman myself.
> You might google for 'beam-expander', as that is a common application of this principle.



Thanks, I'll read through that and see what I can learn! 



jspeybro said:


> I could, but don't have all the necessary details for this setup. I'm in a hurry now so maybe I find time somewhere this week to explain the setup.



If you have the time, that would be really great. This project makes me want to figure out a scaled down version with a smaller emitter for a Maglite...


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## Al Combs (Jul 14, 2010)

EasyB said:


> I actually went through anchor optics, which is connected with edmund optics somehow. The lenses were fairly inexpensive compared to what you'd get at edmund optics. I don't think I had this exact design in mind when I purchased the lenses. Got a bit lucky I guess. I picked the small lens because it has a very high diameter:focal length ratio. 47mm diameter, 21mm focal length. I picked the fresnel lens because it's big and round.
> 
> I'll try and get a good side shot with the beam on.


So the small DCX condenser is AX27459 and the 13" Fresnel lens is AX27363? Nice job on the smoke picture. It looks like you just position the collector so the cone of light it creates is the size of your Fresnel lens, at the point the Fresnel comes into focus. This is one of those projects the more I look, the more I like it.:twothumbs

If it's not too ghetto, perhaps the right size black bucket would help cut down on the glare when you're using it long distance. A box made of ¼" plywood and painted flat black on the inside would be even better. A small square hole at the bottom would give your heatsink breathing room and a means to reach the on/off switch.


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## EasyB (Jul 15, 2010)

Al Combs said:


> So the small DCX condenser is AX27459 and the 13" Fresnel lens is AX27363? Nice job on the smoke picture. It looks like you just position the collector so the cone of light it creates is the size of your Fresnel lens, at the point the Fresnel comes into focus. This is one of those projects the more I look, the more I like it.:twothumbs
> 
> If it's not too ghetto, perhaps the right size black bucket would help cut down on the glare when you're using it long distance. A box made of ¼" plywood and painted flat black on the inside would be even better. A small square hole at the bottom would give your heatsink breathing room and a means to reach the on/off switch.



Yep those are the part numbers that I got. For getting the lens distances right I moved the fresnel lens so that the image is focused then I moved the small lens so the cone fills the fresnel lens, then I repeat those two steps till it's good enough. A glare reducing enclosure would be nice but it would have to be light.


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## Walterk (Jul 16, 2010)

Or a black coat of black fabric.


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## bansuri (Jul 17, 2010)

NOW I see 'em! WOW! Great job man!!


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## jspeybro (Jul 18, 2010)

EasyB said:


> Yep those are the part numbers that I got. For getting the lens distances right I moved the fresnel lens so that the image is focused then I moved the small lens so the cone fills the fresnel lens, then I repeat those two steps till it's good enough. A glare reducing enclosure would be nice but it would have to be light.



can you tell me the distance between the led die and the back of the first lens?
the same for the second lens would also be good to verify the calculation.

1 difficulty with calculating this setup is the use of the first lens which is quite thick. I will see how close a thin lens approximation comes to the reality. The thing is that this calculation would be correct if you use the principal planes of the first lens to measure/set distances, but that info is not available at the anchor website.


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## EasyB (Jul 18, 2010)

jspeybro said:


> can you tell me the distance between the led die and the back of the first lens?
> the same for the second lens would also be good to verify the calculation.
> 
> 1 difficulty with calculating this setup is the use of the first lens which is quite thick. I will see how close a thin lens approximation comes to the reality. The thing is that this calculation would be correct if you use the principal planes of the first lens to measure/set distances, but that info is not available at the anchor website.



The LED (not the dome) is about .5cm from the back of the first lens. The LED is about 35cm from the fresnel lens. I have some image size data that might help you too. The image is 17cm 3m from the fresnel lens and 28cm 10m from the lens.


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## wechnivag (Oct 28, 2010)

Can you re-upload the photos on photobucket or imageshack? This is killing me!!


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## ledlensert7 (May 19, 2011)

just been searching through cpf for a maximium throw sort of project- wow i think this beats anything i had ever expected! that is amazing.

Another project added to the list!:naughty:


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## LEDAdd1ct (Aug 3, 2011)

Wow, very cool build!


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## Dannnn (Aug 5, 2011)

Amazing!! A carbon fiber shell would be great on that, and it's simple/cheap to do.


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## vestureofblood (Oct 19, 2011)

Hi EasyB,

For this project did you focus the LED with the first small aspherical lens so that it was as tight as possible, meaning so it showed the image of the die?


Thanks


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## finges (Oct 20, 2011)

vestureofblood said:


> Hi EasyB,
> 
> For this project did you focus the LED with the first small aspherical lens so that it was as tight as possible, meaning so it showed the image of the die?
> 
> ...


in the pictures, the aspherical lens is very close to the led, so, in my experience, it would create a very wide beam. 
if the asperical lens is further away from the led the beam tightens till it shows the actuall projection of the die.
correct me if i'm wrong


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## Walterk (Oct 20, 2011)

finges said:


> in the pictures, the aspherical lens is very close to the led, so, in my experience, it would create a very wide beam.
> if the asperical lens is further away from the led the beam tightens till it shows the actuall projection of the die.
> correct me if i'm wrong



The first lens close to the led, determines how much of the light is projected on the big lens. 
A wider light beam inbetween led and the big lens, affects the effective aperture of the system exiting by the big lens, and thus throw.

I built a similar light, and made it focusable by moving the led, the lenses are fixated optimized for throw.
It is hard to predict the behaviour excatly when using two lenses, I've tried. 
Having the big lens covered in light from the led is the most important part.
Using a small led (point source) gives a more narrow beam.


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## Al Combs (Oct 20, 2011)

vestureofblood said:


> Hi EasyB,
> 
> For this project did you focus the LED with the first small aspherical lens so that it was as tight as possible, meaning so it showed the image of the die?
> 
> ...


+1 to Walterk's bead on it.

See post #55 for a good picture and #58 for a brief explanation. The small condenser lens next to the LED adjusts the size of the beam angle to match the clear aperture of the Fresnel lens. The Fresnel lens in front is for adjusting the focus on distant objects. Moving the condenser does have an affect on focus but its real function is to collect as much light as possible from the LED. The "tight as possible" aspect of the system is controlled the the Fresnel lens focal length.

Edit:


EasyB said:


> A short focal length lens collects most of the light from the LED and the large fresnel lens focuses it far away. The LED is actually inside the focal length of the small lens, creating a virtual image that the large lens sees.


I was just reading this post again and noticed EasyB explains the function of each lens below the 2nd picture in post #1.


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## xul (Oct 20, 2011)

EasyB said:


> That tower is about 250 meters away.


So if it's a 30 meter high tower and 1/3 illuminated this is a field angle of 2{arcsin(10/250)} = 5 degrees.

BTW, this post is mathematically incorrect! I should write out the formulas before posting, no matter how simple I think they are.


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## tobrien (Jul 20, 2012)

do you have a parts list? I'd love to attempt one lol


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## hoffmyster86 (Jul 23, 2012)

ok! wheres batman? hol  cool.


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