Zelandeth
Flashlight Enthusiast
Well...it's not a flashlight, technically speaking. Presently it's held together by rubber bands, will power, and is tied to a mains power socket by a ridiculously short power cord. but I figured you guys might want a look anyway.
(Note, all pics apart from the beamshots are a early version of the test rig, I refined it somewhat after that, was just wanting to see if it would focus at all in the early pics).
Firstly, the lamp in question: a General Electric 20W CMH-TC metal halide lamp, the specs of which can be found on the following page from www.lamptech.co.uk.
Powering that up on its own was impressive...as a point source anyway. However, having no idea of the amount of runtime on the bulb, was also somewhat unnerving (MH lamps generally should be operated only in fully enclosed luminaires, as the lamps occasionally explode when at the end of their life). Also, I wanted to know what would happen if all that light was focussed. Suddenly, I realised that I might have just the thing...
That light has an aluminium reflector, pretty large (~110mm as I remember), with a very thick glass lens. Is also set up to handle the heat from a 50W halogen bulb, so a 20W MH one should be no bother. So, let's see...will the bulb fit through the hole in the reflector (I ain't making it bigger, I want it back when I'm done!)...
PERFECT fit!
Okay, that established, time to figure out some way of holding everything together, and focus it. To do this, I screwed the lamp socket onto a piece of what I THINK is fibreboard of some kind, has been proven to be uninterested in burning though, as I often rest the soldering iron on it, and it never so much as smoulders. This ain't long term anyway, is just a test lash-up! If you make something similar yourself though, PLEASE use a suitable material to mount the lampholder to...not wood of any kind.
Next...how the (£**)"~# am I going to hold the reflector in place??? /ubbthreads/images/graemlins/confused.gif As it turned out, the NEAR perfect solution to that was a metal slinky! Sitting on the base around the lampholder, it held the reflector NEARLY the perfect height over the lamp. Not quite perfect, had a bit of a doghnut hole in the beam, but it proved to me that it could be done...and gave me a chance to snap a shot of the glow of the lamp cooling down.
Also, that reflector/lens should be capable of containing an exploding lamp in the unlikely event that it happened, saving me from me having to deal with bits of quartz at 500 degrees zapping over the room if the worst happened.
A couple of hours later, I came back in, and looked at this again, while snacking on some Pringles...then it hit me, how I could make a temporary spacer...and I was holding it in my hand, of course, a bit of Pringles tube! Five minutes and a broken set of scissors later, I had this.
/ubbthreads/images/graemlins/ooo.gif /ubbthreads/images/graemlins/cool.gif /ubbthreads/images/graemlins/ooo.gif
It's worth noting that in the above shot, my camera's auto exposure control just took one look at it, and went to hide in the corner. That room is actually pretty brightly lit by daylight, not direct sunlight, but it ain't dark! Well, at least the colour's accurate. The beam then, pretty easy to describe. The Hotshot. Which TOTALLY overloaded the camera, is ridiculously intense, from about 10 feet, is about 15cm across, the bright corona, slightly greater in brighteness to the spot of a stock 5D Mag, is about 2 feet across at that distance, and a wider corona nearly covering the whole hight of the wall, which is still nearly capable of drowining out a 1W LS light! I want to put one of these things in a flashlight now! Beam is beautifully smooth, the transition between the parts of the beam is sharp, but there's not another ring to be seen. Only real artefact is the "bite" taken out of the beam by the return wire for the arc tube. The pic is a waste of time really, the middle corona's all that's visible really! Will try to get another one soon.
By this time, it's been running for half an hour, and the only thing that's noticably hot is the lens. Back of the reflector's warm, but not too hot to touch. Will stop panicing about the cardboard reflector spacer for now then.
I eventally figured out a way of holding the reflector in place with some drawing pins inserted into the rubber lens retainer, rubber bands looped around them, and clipped onto the base (pics to follow), which then meant I could try to capture the best thing about this, the highly visible beam. Camera doesn't like this kind of thing, but I managed!
It actually appears considerably brighter to the eye, but you get the idea.
It's a shame these lamps are so fragile, aside from the run up time (~a minute for this one), and that, they're brilliant! A point source like that is just sooo easy to focus, this is with the reflector out of a $20 light, move upmarket, and you could probably get those photons to do all kinds of wierd and wonderful things.
Ah well, will get a few more shots of this, then rewire things and see what happens when I stick a 35W lamp in the same reflector...Think getting introduced to HID things was a bad idea...I'm hooked now! /ubbthreads/images/graemlins/crazy.gif
Will probably have a couple of pics to follow later. For now, enjoy having a laugh at my crude (to say the least) setup, and feel free to ask any questions. And if you do decide to mess around with this kinda stuff, BE CAREFUL.
(Note, all pics apart from the beamshots are a early version of the test rig, I refined it somewhat after that, was just wanting to see if it would focus at all in the early pics).
Firstly, the lamp in question: a General Electric 20W CMH-TC metal halide lamp, the specs of which can be found on the following page from www.lamptech.co.uk.
Powering that up on its own was impressive...as a point source anyway. However, having no idea of the amount of runtime on the bulb, was also somewhat unnerving (MH lamps generally should be operated only in fully enclosed luminaires, as the lamps occasionally explode when at the end of their life). Also, I wanted to know what would happen if all that light was focussed. Suddenly, I realised that I might have just the thing...
That light has an aluminium reflector, pretty large (~110mm as I remember), with a very thick glass lens. Is also set up to handle the heat from a 50W halogen bulb, so a 20W MH one should be no bother. So, let's see...will the bulb fit through the hole in the reflector (I ain't making it bigger, I want it back when I'm done!)...
PERFECT fit!
Okay, that established, time to figure out some way of holding everything together, and focus it. To do this, I screwed the lamp socket onto a piece of what I THINK is fibreboard of some kind, has been proven to be uninterested in burning though, as I often rest the soldering iron on it, and it never so much as smoulders. This ain't long term anyway, is just a test lash-up! If you make something similar yourself though, PLEASE use a suitable material to mount the lampholder to...not wood of any kind.
Next...how the (£**)"~# am I going to hold the reflector in place??? /ubbthreads/images/graemlins/confused.gif As it turned out, the NEAR perfect solution to that was a metal slinky! Sitting on the base around the lampholder, it held the reflector NEARLY the perfect height over the lamp. Not quite perfect, had a bit of a doghnut hole in the beam, but it proved to me that it could be done...and gave me a chance to snap a shot of the glow of the lamp cooling down.
Also, that reflector/lens should be capable of containing an exploding lamp in the unlikely event that it happened, saving me from me having to deal with bits of quartz at 500 degrees zapping over the room if the worst happened.
A couple of hours later, I came back in, and looked at this again, while snacking on some Pringles...then it hit me, how I could make a temporary spacer...and I was holding it in my hand, of course, a bit of Pringles tube! Five minutes and a broken set of scissors later, I had this.
/ubbthreads/images/graemlins/ooo.gif /ubbthreads/images/graemlins/cool.gif /ubbthreads/images/graemlins/ooo.gif
It's worth noting that in the above shot, my camera's auto exposure control just took one look at it, and went to hide in the corner. That room is actually pretty brightly lit by daylight, not direct sunlight, but it ain't dark! Well, at least the colour's accurate. The beam then, pretty easy to describe. The Hotshot. Which TOTALLY overloaded the camera, is ridiculously intense, from about 10 feet, is about 15cm across, the bright corona, slightly greater in brighteness to the spot of a stock 5D Mag, is about 2 feet across at that distance, and a wider corona nearly covering the whole hight of the wall, which is still nearly capable of drowining out a 1W LS light! I want to put one of these things in a flashlight now! Beam is beautifully smooth, the transition between the parts of the beam is sharp, but there's not another ring to be seen. Only real artefact is the "bite" taken out of the beam by the return wire for the arc tube. The pic is a waste of time really, the middle corona's all that's visible really! Will try to get another one soon.
By this time, it's been running for half an hour, and the only thing that's noticably hot is the lens. Back of the reflector's warm, but not too hot to touch. Will stop panicing about the cardboard reflector spacer for now then.
I eventally figured out a way of holding the reflector in place with some drawing pins inserted into the rubber lens retainer, rubber bands looped around them, and clipped onto the base (pics to follow), which then meant I could try to capture the best thing about this, the highly visible beam. Camera doesn't like this kind of thing, but I managed!
It's a shame these lamps are so fragile, aside from the run up time (~a minute for this one), and that, they're brilliant! A point source like that is just sooo easy to focus, this is with the reflector out of a $20 light, move upmarket, and you could probably get those photons to do all kinds of wierd and wonderful things.
Ah well, will get a few more shots of this, then rewire things and see what happens when I stick a 35W lamp in the same reflector...Think getting introduced to HID things was a bad idea...I'm hooked now! /ubbthreads/images/graemlins/crazy.gif
Will probably have a couple of pics to follow later. For now, enjoy having a laugh at my crude (to say the least) setup, and feel free to ask any questions. And if you do decide to mess around with this kinda stuff, BE CAREFUL.
