2nd Mag Dragon on CPF with a BFL lens

After seeing ma_sha1 build his Mag Dragon I decieded to make my own. I am using a cree xr-e r2 driven at 1.4A with a three mode board I bought from download. It is powered by two AW li-ion protected cells. I knew the fly dragon lens was not optamized for the cree. It works OK but not as good as I would have thought. So I took it upon my self to search and harvest a worthy lens for my build. I think I have foud it, I call it the BFL (Big F#$%ing Lens). Enjoy

First some pics of the Fly dragon build. Here is the Mag D adapter inserted in the fly dragon head that way it is totaly focusable.




Here is the battery adapter I made so the MAG will accept the 18650 cells. I used a piece of schedule 80 PVC and pressed it into a normal piece of 3/4 inch PVC.


Here is the other end. The positive nub that sticks into the MAG switch.


Next we have the tailspring mod.




Here is the custom heatsink I made. I cut out copper disks and soldered them together and then lathed it to fit inside the mag. I have three little set screws in the side so I vary the height of the heat sink.




Here is the finished light.






I only took one beam shot from about 10 yards away. The beam is very bright but the lens does not focus really well using the cree led.


And now I present the cheap, free, BFL lens.


Look it can do a head stand.






The inside


It does not look much brighter but the spot is so intense that my camera just does not do it justice. Same distance 10 yards


Here is a shot with the light back 30 feet and a close up of the die image.


Trees are about 100 yards


I wanted to see how far it would go, so here is a map of my plan. The red line is the path of the light. Left side of red line is where I stood, Right side of red line is where my target was, a water tower. It is aproxomately 0.9 miles away. Now I know you have to look hard at the pic but you can see the legs of the water tower. Pic probably would have been better but I don't have a good enough camera and there are to many street lights.


Sorry for the bad pic, you really can see it in person. Look for the little red light at the top of the pic, then look down just a little bit. You can see three legs going down and part of the tank.



Hope you guys enjoy, let me know what you think

:thumbsup:That's quite the beast. Judging from the picture it looks like you may be between 300-400cp. Kind of hard to tell though with that camera. Did it look much more visible in person? Do you have a lux meter? Would be interesting to see what it does. I have a similar light I have been working on. Just been too busy and haven't been feeling well enough to get all the beamshots done. Hopefully I'll get it up next week.

BTW Me thinks with a lens that big it would be good to consider a different form factor. Anyway good work!

Yes it is quite visible, no I do not have a lux meter. what do you mean a different form factor

Congratulations!! You finally finished it.
The Dragon head will work well if you put a SST-50 in there.

As for the BFL, what is lens diameter & Focal length?

Where did you get the That Big lens? Looks awesome!

LED4LYF said:

Yes it is quite visible, no I do not have a lux meter. what do you mean a different form factor

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My guess is that he meant to say Spot Light format, mount a handle on top like Polarian style.

Thanks for the kind words. I am not sure what the diameter of the lens/lenses are, I will take some measurements this weekend. As for where did I get it? My boss brought his old rear projectin TV into work and I took it apart and ther were three of these in there. I took apart the housing and cleaned all the lenses, made a mag head adapter and painted it with hammered black spray paint. I is a 2 lens system I will give som more detail about it over the weekend.

There was a guy played with projection TV lens before, it was really big & he put it into a Garden flare.

I like your BFL style better, might have to look into this :thumbsup:
If you have the TV make & model, let me know.

Holy crap what a head on that thing! Good job though.

Yeah it is pretty big but it is really just for fun. Ma_sha1 I am not sure what brand of TV it was, pretty sure it was not a big name brand.I will look next week and get back to you on the brand and make. Here is a drawing of what the lenses are like. It did have one more lens on the end, I took it out because it did not help the performance at all and it was shaped really wierd. It looked like the collameter lens only oposite the outsides were going in towards eachother.



What is the sku number on DX for the lux meter you use? I think I found it but the range says only 200,000lux how do you measure over that? And also what is the correction factor for that meter? Thanks

LED4LYF said:

Yeah it is pretty big but it is really just for fun.

What is the sku number on DX for the lux meter you use? I think I found it but the range says only 200,000lux how do you measure over that? And also what is the correction factor for that meter? Thanks

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Well, I can't let you have all the fun to yourself, so I have three BFL system coming in:devil:
Each one is about 4.5" diameter, don't know if thre are multiple lens in each of the tube.

My DX meter is the 200,000K model.

You don't read at 1 meter, you read it at 5 or 10 meters.
To read it, I select the 20,000K reading level.
Read it at 10 meters. Than take the read out x100.
If you read at 5 meters, than take the read out x25 to get your lux@ 1 meter.

For example, a 400Klux @ 1 meter will have a read out of 4000lux @ 10 meters. 4000x100= 400,000 lux@ 1 meter.

My triple BFLs:

Those are awsome cheap, simple and pretty decent throw. Let me know which one works the best for you. Where did you find those, ebay? I hope to get a lux meter sometime so I can measure my BFL.

Got them on ebay, no idea what they are, but it's BFL non the less, they are Bausch & Lomb brand,
So I know it's good quality lens, just don't know the EFL of them.

You should def. get a lux meter, human eyes are almost useless in quantifying lux,
they adjust pupil dialation to see that they want to see :devil:

I will try to get one, little short on funds though. How would I figure out my EFL on my BFL? I think those lenses you got are from old stage light spotlights.

I'm building a spotlight using ex-Rear-Proojector lenses - both lenses are 130mm dia - but unfortunately resin - not glass.

The Plano-Convex lens has a focal length of 500mm and the Bi-Convex lens has an fl of 140mm.