Widmer's LED Projection System

[der_wille_zur_macht]

I think you are attempting to have an argument when there is none to be had.

With all due respect, look in the mirror.

 

[BeanAnimal]

With all due respect, look in the mirror.

And with all due respect, will you be looking into it as well my friend? I find your post bothersome, as it is nothing more than an attempt to cause trouble.

I kindly responded to a post you made regarding the output of a 400W mH compared to 70W of LEDs and did so in a kind manner, clearly attempting to avoid giving the impression I wanted to argue with you or question your understanding or motives. I attempted to speak to the scenario you mentioned with regard to what we know about reflectors and output from the different technologies. At least two people have followed and taken my response to you out of context and attempted to turn it into a debate about why LEDs are better. I don't care to participate in that debate and have kindly pointed that out without taking a side one way or the other.

I have not attempted (nor will I) to argue if LEDs are viable for reef lighting or not.

 

[BeanAnimal]

I've never seen a MH reflector that can focus a narrow beam of light from four feet away, but that would be really cool. does such a thing exist?

Yes in different forms... but nothing for reef lighting that is designed to take the entire output of the bulb and focus it over a rectangular area the size of a given tank with no spill.

 

[widmer]

However I've yet to see anyone try their hand at a halide system that could be mounted on the ceiling at 5+ feet away from the tank and produce the same PAR levels with less than 10% light spill - if they did though it would be another great project (hint hint Widmer.)

Thanks for having faith in me that I might be able to make this happen. But to be honest, I'm not sure how possible it would be to get the same effect from a halide without losing a significant amount of the light no matter what reflector you could make.

I could make my statement simple, and say "show me a 70w MH bulb that puts 300 PAR at 4 feet, with almost no spill outside of a 2 square foot area (remember: my fixture uses ~72w)" But why not be thorough...

This is because the halides, though considered to be a point source light, have in fact a MUCH larger area from which the light is emitted. And then on top of that, they emit light 360 degrees, and it must as well pass through a glass casing. Of course LEDs have the clear plastic type casing over the emitter which is similar to the halide, but due to their true pinpoint sized emitter, the light isn't bouncing all over the place, which translates to manageable.

So I believe that a reflector could in fact be designed to project ~90% of the light that leaves the reflector onto a two-square-foot surface, but I'm guessing that this would involve absorbing much of the light that leaves the bulb in the form of "barndoor" shades mentioned earlier in this thread.

And finally, I'm a student. This means I'm very motivated by saving money. So when I was designing a new fixture for the tank, I was very put off by having to replace the halide bulbs every ten or so months at yes $70 or so per bulb. Heck, the cost of bulb replacements alone in three years would pay for the cost of building this fixture. And let's not even mention the electricity savings, or the fun it is to finely-tune the actinic level at any moment to suit my mood.

While there is a bit of healthy(?) argument going on, I would like to say in Bean's defense that he was quite literally pointing out the raw physics behind approximating light. But it is still easy to see how the original post could have been taken as a move to claim that halide would be better to use in the circumstance of my fixture.

But when it comes to efficiency, adaptability, cost savings, and just plain fun, rest assured LED enthusiasts.

 

[widmer]

At least two people have followed and taken my response to you out of context and attempted to turn it into a debate about why LEDs are better.

So it must be everyone elses' misinterpretation....? Bean, I know a lot of us really appreciate your continual help here. For instance, back when I was dealing with whether or not to use silicone grease on the O-rings for my overflow/return, you made excellent points and I am very grateful for that help. However, a trend that no one would deny is that many of your posts do appear to be quite confrontational. It's all in the delivery....Or so very many forum members must be wrong.

 

[der_wille_zur_macht]

Yes in different forms... but nothing for reef lighting that is designed to take the entire output of the bulb and focus it over a rectangular area the size of a given tank with no spill.

I guess that's my point. Your facts that an MH rig could approximate the projector effect achieved here are quite true, in the purest sense - sure, if we could design an ideal reflector/lens, it would be possible for an MH to be used in this manner. However, I've never seen such a reflector/lens - or at least not a reasonable one in terms of cost/performance/time involved. So, if it doesn't exist, why hypothesize about it? LEDs have a very clear advantage in this regard, so why even bring it up?

 

[widmer]

However, I've never seen such a reflector/lens - or at least not a reasonable one in terms of cost/performance/time involved.

I believe that it's probably because this wouldn't be so feasible in real life. As I kind of said above, I don't believe the standard halide is quite enough of a point-source light to really project a narrow beam without sacrificing a great deal of efficiency. And after all, one of the big points behind halides is efficiency.

 

[BeanAnimal]

So it must be everyone elses' misinterpretation....? Bean, I know a lot of us really appreciate your continual help here. For instance, back when I was dealing with whether or not to use silicone grease on the O-rings for my overflow/return, you made excellent points and I am very grateful for that help. However, a trend that no one would deny is that many of your posts do appear to be quite confrontational. It's all in the delivery....Or so very many forum members must be wrong.

Thanks, i am glad to help when I can.

When people have a strong opinion about something, they tend to read into things far more than they should.

Cconsidering the number of posts I have made here and the number of people I have interacted with, there are actually very few forum members that I have ever had a problem with.

I have enjoyed reading about your project and hope that it turns out well long term.

 

[BeanAnimal]

I guess that's my point. Your facts that an MH rig could approximate the projector effect achieved here are quite true, in the purest sense - sure, if we could design an ideal reflector/lens, it would be possible for an MH to be used in this manner. However, I've never seen such a reflector/lens - or at least not a reasonable one in terms of cost/performance/time involved. So, if it doesn't exist, why hypothesize about it? LEDs have a very clear advantage in this regard, so why even bring it up?

I simply brought it up as a learning tool. Remember (as I stated in the initial post) not everybody has the same understanding of light as you or I. By placing known quantities side by side, it is easier for people to gain a real world, useful understanding of why and how things work. In turn, when they decide something is "better" their opinion is informed rather than correct by misinformed by chance.

Simply put... "The more you know..."

 

[BeanAnimal]

I believe that it's probably because this wouldn't be so feasible in real life. As I kind of said above, I don't believe the standard halide is quite enough of a point-source light to really project a narrow beam without sacrificing a great deal of efficiency. And after all, one of the big points behind halides is efficiency.

It is a matter of application more than ability. When a light source as intense as a halide needs to be focused, we usually use a lens or series of lenses to ensure EVEN lighting and eliminate the point. That said, projector style headlamps and other high efficiency lighting products based on HID lamps are certainly being developed now that there is a demand for efficient lighting products. Our hobby is not even a blip on the radar with regard to R&D for such products. We just get what spills over from industry and adapt it the best we can. I don't ever see a demand for a highly efficient HID reef spotlight that needs a 4'-5' focus

Off into the snow storm to get pizza... have fun folks.

 

[Flanders]

By placing known quantities side by side, it is easier for people to gain a real world, useful understanding of why and how things work.

I'm sorry to belabor the point, but again, a hypothetical metal halide reflector/lens system that may never exist for an aquarium application cannot be described as a "known quantity." it's interesting discussion for sure, but the only known quantity in here is the PAR numbers from widmer's fixture.

 

[BeanAnimal]

I'm sorry to belabor the point, but again, a hypothetical metal halide reflector/lens system that may never exist for an aquarium application cannot be described as a "known quantity." it's interesting discussion for sure, but the only known quantity in here is the PAR numbers from widmer's fixture.

You simply have missed the entire point and context of the post, light and its behavior are the known quantity. Honestly, this is getting kind of silly.

 

[Flanders]

yeah, it sure is.

 

[H20ENG]

There are light fixtures for spot lighting with halides, argon lamps, etc for theatrical applications. They are long and large... as must be your wallet to aquire them.

Widmer,
Great job on the fixture! I applaud you for taking the time to research, learn, and apply a new skill for a nice DIY!

 

[onecoder]

Bean, I was not implying or trying to start a LED/Halide debate. You are correct light behavior is predictable, and Halide, VHO, Incandesent, any light source could be reflected, focused, ect to "spot light". (with varying intensities)

I just wanted to bring up that there are many other things to concider when looking at lighting.

Thanks for being willing to help to everyone and for debating. Only by discussion and experimentation are we able to find alternatives to what idustry is packaging for us.

 

[BeanAnimal]

Bean, I was not implying or trying to start a LED/Halide debate. You are correct light behavior is predictable, and Halide, VHO, Incandesent, any light source could be reflected, focused, ect to "spot light". (with varying intensities)

I just wanted to bring up that there are many other things to concider when looking at lighting.

Thanks for being willing to help to everyone and for debating. Only by discussion and experimentation are we able to find alternatives to what idustry is packaging for us.

Yes there are certainly a broad range of considerations when selecting a suitable light source for a project. As of late I try to avoid the debate with regard to pros and cons of different types of lighting, as it never turns out well. It is nice to see that so many people and companies are starting to look outside the box instead of just rebranding what industry passes on to us.

 

[salty joe]

Wow, Widmer that's an outstanding build! Thanks for sharing.
With your 8° optics, does that mean that the beam of light coming down is 8° from vertical?

 

[BeanAnimal]

The beam projected from each LED is an 8° cone

 

[der_wille_zur_macht]

The optics are named based on the FWHM standard. What that means is basically that, at an 8 degree cone width, you'll find that the light is half the maximum in the very center of the cone. That makes it sound like half the light is outside the cone, but it's typically less than that (intensity is usually dropping off VERY fast at that point), though it will vary based on the distribution of the particular lens.

 

[salty joe]

Well the results are in. Our very own Skippyreef came over last night with his PAR meter. I turned the lights up to full intensity and we measured all over the tank and surrounding area. Found some interesting data:

General area toward the center of the tank near water surface (48" from fixture): ~300
At sandbed, near center of tank (60" from fixture): ~200
Middle of water column, at left and right ends of tank: ~150
Outside of tank, just outside of glass at water level: ~40
Outside of tank, a foot from the glass at water level: ~5

Interpretation: The 45 PAR That I'm getting around the perimeter of the glass tells me that the lenses are not perfectly efficient at collecting and projecting the light. But for as little as I know about what the actual PAR numbers correlate to, I'll take Skippy's word for it that this is pretty decent for ~70 watts of light 5 feet off the tank.

For the PAR junkies out there, we could probably extrapolate that if I were using the same number of the much more efficient Cree XP-G's with similar lenses I would be reading 400 PAR, and with better lenses maybe 500 PAR or beyond. Furthermore, if 24 LEDs were employed (which certainly could have fit on my two heatsinks if they were elbow to elbow), we could potentially multiply this figure by 1.33, and be pushing 700 PAR.

All things considered I would say that I'm getting pretty decent PAR coming off of my 9 blue and 9 white XR-E LEDs on the ceiling of the room.

Thanks for bringing over the meter Skippy

Did you happen to take a reading at say, 1 foot or 2 feet from the fixture? It is my understanding that light obeys the inverse square root law. So if you are getting 300 par at 4 feet, would that mean that you are getting 90,000 par at 2 feet? That just doesn't sound right. But it would be interesting to know how much you lose due to the height of your fixture. Thanks again,
Joe