# What would the ideal reflector look like to you?



## EseriesModder (Mar 9, 2017)

Would it be a curved dish? Would it be a straight sided cone? Maybe it would be rounded at the bottom, or would it flair inwards towards the top? Smooth? Orange peeled? Concentric spirals? It could even be stepped. What shape would you choose and why?

I'll be making drop-in reflectors to replace stock plastic ones. Reflector geometry is something I know a lot of you are passionate about, so I'm hoping to open up a dialog.


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## gadget_lover (Mar 12, 2017)

It does not matter what the reflector looks like. What matters is the beam that it produces.

I like a beam that has a bit of throw, with no discernible hot spot. That allows a small 3 watt LED to illuminate an entire back yard. Which reflector will give you that depends on the light source, the size that you want and the space considerations. I like a TIR in my small lights due to their efficiency. 

Dan


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## EseriesModder (Mar 13, 2017)

"It does not matter what the reflector looks like" seems like a very dismissive answer.

Firstly, it does, the reflector is the second most important part of the light behind the bulb.

Secondly, even if that were true it could be applied to the entire flashlight. And yet people constantly go after more attractive lights when all things are considered equal.

Some of the companies working on TIR have been playing around with intricate surface patterns for years. To someone who dismisses the importance of the reflector spirals, ridges, and steps might seem like needless aesthetics but there can be a lot of thought put into them, at least as much as a well designed Fresnel lens.

It just seems unfortunate that we limit ourselves to smooth or orange peeled when there are other choices.

But I don’t want to focus on surface pattern. The angle at which the light is being reflected and the curvature of the reflector play a crucial part as well, though in these cases what is possible is usually limited by the space available. I want to know what people prefer, or what they’ve successfully seen applied in the lights they use.

I’m just a guy who likes shaping metal, and enjoys over thinking things. I intend to make several reflectors out of tarnish resistant silver to see how they compare. If anyone would like to make any suggestions, I’d be happy to see how they work.

Please don’t let this become about optics. That’s a different subject that belongs in the general discussion area. Thank you.


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## KITROBASKIN (Mar 14, 2017)

Looking forward to your reports about tarnish resistant silver reflectors. Might you integrate them into heat management, given that silver transfers heat very well?
For many of us, though, highly functional is highly beautiful, No matter the aesthetics. Sorry if I did not answer what you were hoping for. Have you read about wavien collars?


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## fivemega (Mar 14, 2017)

http://www.candlepowerforums.com/vb...-M*g-Reflector-by-Fivemega-(Outdoor-Beamshots)


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## EseriesModder (Mar 14, 2017)

That's awesome that someone actually makes a mag-lite reflector. I didn't find any, but then again I didn't search very hard. I'm doing this for the fun of it, not to fill my need for a metal reflector. In fact, I don't even own a mag-lite yet. I keep meaning to order one on amazon, but I still haven't nailed down which size I'd prefer. I'm leaning towards a three D-cell model, so I can eventually use rechargeable batteries in it. For now I'm still just messing around with scrap sheets and scavenged LEDs. Thanks for the resource, though, fivemega. I'll be sure to look into it further.

And to reply to kitrobaskin, I'm actually very excited to see how the silver will effect heat management. I originally learned to form metal by making copper vessels before moving onto cookware. Making a tall ornate vase might be more labor intensive, but making a deep cooking pot is a far more subtle art, because when copper or silver is over worked the thermal conductivity can be effected, meaning the metal heats unevenly. If I make these correctly they should wick away heat pretty quickly, though not as quickly as if I were using fine silver (Thats 99.9% silver, vs the 95.5% in the argentium silver or comparable alloys I'll be using. Sterling is 92.5%, just for reference.)

And on the topic of wavien collars I'm really glad you brought it up, because it was originally one of my reasons for starting this project. Thank you for reminding me, as it slipped my mind until now, and none of those specialized tools have made it onto my checklist. In addition to the wooden dapping block I'll be making for the regular reflectors, I'll also need to machine a specialized t-stake to help me form that inward facing lip. I'm embarrassingly excited about that prospect. Hopefully I’ll get to start that this Thursday.


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## gadget_lover (Mar 15, 2017)

EseriesModder said:


> "It does not matter what the reflector looks like" seems like a very dismissive answer.



That's because you missed the very important point that followed. The post should have been quite helpful because the beam is much more important than the reflector appearance. The appearance is a result of the functionality, not the other way around.

For example; 

1)You use a straight sided cone if you want a very dispersed beam.

2)A deep dish that is not focused in any way will often provide a very ugly beam.

3) An orange peel will smooth out the beam if the light source is uneven, reducing rings and other artifacts.

4) A parabolic can give a tightly focused beam that throws far.

5) A reverse reflector can give a very, very tightly focused beam with almost no light outside the main beam.

In my 100+ light collection, I have all of the above as well as those using TIR optics and lenses. I don't think that the appearance of the reflector was a deciding factor in any of the purchases. 

Like I said, the remark was helpful, not dismissive.


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## EseriesModder (Mar 16, 2017)

I didn't miss it, I just found the following three sentences to be lacking in detail. They mostly added up to a statement of preference without constructive information, and what little was there was too generalized to be encouraging. I didn't take offense too it, and I apologize if my reply didn't come across as friendly. That wasn't my intention. I was simply trying to respond and create a more productive discussion.

of course the beam is important, there is no doubt about that, but the beam is the end result.

You were very detailed in your response, and I thank you for that. You even went ahead and numbered your points of information, which I appreciate and enjoy. You went beyond what is required.

I'm sorry if I disagree with you.

If you'd like to elaborate on your experiences with #2, unfocused reflectors, or #5, reverse reflectors, that would be welcome and appreciated.


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## gadget_lover (Mar 16, 2017)

It's OK go disagree. After all, I disagreed too. 

I'll address #2. I'm assuming that you know about the physics "Law of Reflection". If not, take a look at http://www.physicsclassroom.com/class/refln/Lesson-1/The-Law-of-Reflection for an explanation.

When you make a randomly shaped bowl, the light will reflect off the surface according to the law of reflections. Since light is additive, this can create rings where more light happens to be reflected to the same areas. Uneven lighting makes it hard to see clearly. Spinning the bowl should make it pretty consistent as far as side to side, but will not ensure that the same amount of light is going where you want it. A typical shape for a focused beam reflector is parabolic. A typical shape for a flood beam is very shallow.

And of course, some light never touches the reflector, so you have to take that into account.

Reverse reflectors are just what they sound like. The light source is suspended over the reflector, and 100% of the light hits the reflector and bounces out the front. Like all reflectors, the law of reflections rules, and the resulting reflector is similar to a hemisphere.


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## degarb (Mar 18, 2017)

Subscribing to thread for later deeper reading. 

I never before heard of freshnal lenses for flashlight. A quick Google brings up one guy buying a 3 dollar drug store 7x10 inch sheet, holding a foot in front of led flashlight to get a super thrower. Never tried. Then on Chinese abstract https://www.osapublishing.org/ao/abstract.cfm?uri=ao-55-4-712

I always thought there was a mathematical formula for elliptical shape, which is different for different lens. Though oddly I can use same reflector on xml or xpg, only the xpg is 2x as bright and needs half the juice to see same things. However, xre and rebels, lux1s had radically different reflectors. On xml or xpl, 2 watts, 2s18650 buck, and 35 mm smooth is perfect balance of throw, spill, runtime. Though my 30mm has a 4k candela Hotspot, surrounded by a 30 degree bright Hotspot and wide spill to 110 degrees: which is bare minimum 2 meter inspection brightness, yet the 372 [email protected] is about perfect 90 percent of a workday of bouncing from 1meter to 2 meters inspection of micro nit picking. In the end my five is 2 degrees on center, my cones are 15 degrees or under, my rods can't see color well or detail. However, mathematics tells me you need near 2x the juice going form 12 degree Hotspot to 16 degrees, and you gain little, not worth halving the runtime.


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## degarb (Mar 18, 2017)

1000 lux, per my tests, seem to be minimum lux for inspection. You need 4000 candela for 1000 lux for 2 meter viewing. Most work is a bounce between 1 meter and 2 meter:90%of time. A fact underlined when my optometrist ruined my 6 foot and under vision by forcing me into superman 20/8 contacts, from my 20/25 astigmatism. 90 percent of my eyesight ruined. It cost mr $2500 to fix. Anyway, Upper teen lux is too bright. Outside, working in shade, 700 to 7000 lux is typical. But I pull out headlamp when lux drops to 1000, half hour before dusk and heavily cloudy days on covered porches. Obviously, lux, candela, lumens, are all different things. The allowable runtime, allowable weight, top emitter efficiency, top driver efficiency, top battery energy density per weight/volume, lens antiflectivity, are all thing that are variables that are absolute. After those are calculated, you have xxx lumens to shape into some thing that can do the job required. If you had unlimited resource, lumens, there would never, ever be a need for any reflector or optic. The wise choice of beam shape optimizes how well you will see at your final allowance of lumens!!! The best quote is, " If you are looking for something or navigating, you want flood:if you are looking at something you want throw (1000lux)". One exception is you want throw looking for something in a messy area, especially if object has little contrast with surroundings. And you may want throw and peripheral, going down a mountain at 30 mph on a bike. Plastic reflectors I own, you can see light leaking through and I can measure a 20 percent drop in lumens, their lux can be good. Also, epoxy star electric areas, to water proof, cut holes/slots in bezel to open up bezel for chimney effect, and your aluminum reflector/inside of bezel works to release heat into the air, increasing led efficiency. I made water proof seal between reflector and star. I also abandoned the cylinder, went for a cpu styled, finned heat sink. Headlamp and wrist light.

On a personal note, I have had many headlamps, most failures. One headlamp, with too little runtime for a tasklight, due to mathematics of its greedy beam shape, had Hotspot as wide as my shoulders looking at my feet and Corona about 120 degrees. I realized this is a flood light for my standards, as it can illuminate both pages of a book, and covers my eye cones generously with the Hotspot and my rods with the Corona. In my lifetime, a floodier light would be a foolish waste of juice. Just a thought. Shoulder wide Hotspot, looking down from headlamp: maybe with jacket on, probably roughly (though not always) convertible through many body types of larger and smaller people with normal body proportions. Just a thought that seems empirical.


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## EseriesModder (Mar 19, 2017)

Progress report:

So, the snow this week kept me from doing any machine work. I settled for using the beak of my anvil to get general shapes, but I don't foresee that being very helpful in the long run. I think a Heikki Seppa approach to this will give the best results, so I'll be using wooden dapping blocks to do most of the work. Those will be ready hopefully by the second or third week of april. In the mean time I'll be spending some of my spare time machining hook stakes for forming lips. They'll be something like a miniature snarling iron. That's the only way I can imagine making a reflector with an integrated collar. It wont be necessary for everything, just the fun stuff.

I'm still procrastinating on buying a mag-lite, because I keep hoping to find one sitting forgotten in the basement or garage. That's hopeless, though, and I know I'll eventually have to invest in one. But then I'll want to get drop-ins for it... and then the lens wont be to my liking, so I'll have to go find the right sized crystal... and then the o-rings, and the switches, and so on and so forth. So I'll keep procrastinating for as long as I can. In the mean time I have a 6-9v drop-in thats got nothing else to do. It's on a little pedestal, to make focusing a bit easier.

In in response to degarb, that link of yours was an interesting read. 3-6% error seems pretty sloppy. It makes me wonder whether part of the error might be due to the setting of the material used, because I've experienced shrinkage in that range when dealing with clear resins and epoxies. Still, part of me wants to hope that they took that into consideration beforehand. I wish I had access to the figures, to see how tall their Vs were.

I'll get back to working on reflectors now.

_edit:_

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-17-20-17916&id=186173

More off topic reading, for anyone who might be interested.


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## brickbat (Mar 26, 2017)

EseriesModder said:


> ... What would the ideal reflector look like to you?...
> 
> ...Please don’t let this become about optics....



Umm, with all due respect, let form follow function. A reflector isn't put in a flashlight to look cool. It's there to gather and focus light.


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## EseriesModder (May 15, 2017)

Well, dapping blocks took a while. I'll be stepping up my polishing equipment in the next month or so, along with a few more tools. New lenses and filters are in the mail from amazon.

Lost a metal lathe last thursday. I'm trying not to dwell on it. It'll take a while to replace, since I'll have to wait around for a good deal.

The response to this thread worries me. I like to be precise. I like forms with attention paid to their ratios and proportions. I like aesthetics, and I appreciate the craftsmanships and artistry required to take a well thought out functional form and take it that extra step. It's that extra attention to detail that give objects a character of their own. I'm coming here to a forum for people who appreciate these fantastic little machines, inviting you all to appreciate one specific detail. And my reasons for this are selfish, i admit. I want to over engineer these reflectors I am making.

But, I feel I need to explain. If you think that level of thought is wasted on something as simple as a reflector, you don't understand that I'm doing this for every other aspect of the flashlight as well. I'm thinking beyond the bevel, body, and tailcap; down to details like gasket sizes and thread angles. Every internal and external diameter of a design has to be measured, considered, and reconsidered.

I think it was a mistake to make an account here. I've been silently reading these threads without one for a very long time, and I don't think I've gained anything from coming here and sharing with you all. I still feel like I learn a lot from reading about what talented individuals put together, but perhaps this community isn't the best place to attempt to have these discussions.

I apologize to everybody.

I'll keep updating this for myself. If it takes a while between updates that's normal for me, just be patient.


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## archimedes (May 17, 2017)

Have you seen this thread ?

http://www.candlepowerforums.com/vb/showthread.php?91615-quot-McR-xx-quot-Reflectors

Some important history there....


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## EseriesModder (May 18, 2017)

No, I had not. Thank you for the link, Archimedes. That's quite helpful actually.


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## archimedes (May 18, 2017)

EseriesModder said:


> No, I had not. Thank you for the link, Archimedes. That's quite helpful actually.


Cheers !


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## degarb (May 19, 2017)

The ideal reflector would be oval, look like a slight crushed round one. 

I don't know if even possible, mathematically. But a hotspot/coronal dimension ratio of wider width to height - probably a HDTV ratio- would be more ideal and efficient than round. 

Normal xml 12 degree hot spot covers most of the eye cones, that are clustered below 15 degrees. The rods are proven not even able to see color, just movement. Thus, few cones must be present in periphery... So, traditional Hotspot, Corona out towards 120 degrees, covers most vision. The weak part is getting a full 15 degree and full 120, because led and battery not reached enough efficiency and power to achieve this at a 4to8 candela Hotspot, which is needed for 45 degree viewing a 2 meter object and maintaining 1000 lux. Also the wide ratio, consistent with 2 eyes, has only been attempted by the tir. For some reason, I don't like the tunnel vision of a tir, and I always have measured a 30 percent lumen drop, compared to aluminum smo and AR glass. At least, on tir I have bought. I know they have claims.


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## EseriesModder (Jun 2, 2017)

degarb, I've played around with symmetrical ovals, mostly because I like the feel of those old 4 AA cell lights that had two stacks of batteries running side by side. For me it was a purely form over function thing, in an ugly case, but now I'll go back and play with it some more. I won't tackle the rod and cone argument until I can safely say I understand most aspects of it, but oval reflectors have a surprising amount of character.

In other news, I'm surprised to find my reflectors getting suddenly much bigger. It wasn't intentional, just a reaction of mixing work with play. I'm using legit scrap metals on these guys. Mostly aluminum, but I'm using bare copper and brass for a few of the lights where we need amber tints, and it's kind of nice. I know the heat will tarnish them quickly, but they're LED lights, so they should be fine through one photoshoot. I'll see how everything translates back down when I have more free time.


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## PeterH (Jul 3, 2017)

I have to agree that reflector shape should follow from desired beam shape. That leaves the question of what is the ideal beam shape? I my opinion an ideal beam shape would be characterized mostly by width angle, how wide being a function of intended use. Light distributed smoothly across the area. Probably brightest at the center and dimmer near the edges. A hot spot in the center is not my idea of a good beam shape. Instead, reflected light needs to be spread across the area of the direct beam.


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## ssanasisredna (Jul 11, 2017)

I apologize in advance for my reply, but I can't see any other way to put it.

Basically this thread is someone who has no idea (from what I can tell) about how to design a reflector asking other people (who have no idea how to design a reflector), how to design a reflector. I don't see it ending well.

As has been repeated often in this thread, form follow function. You don't ask someone who has no idea how to design a reflector .... how to design a reflector. You are never going to get the right answer. However, you can ask them what they want the beam to look like .... of which you have gotten several good replies, none of which are likely to be the same because no beam is perfect for all situations.

Starting out with the premise of making metal reflectors to replace "stock plastic ones" may seem like an admirable goal, but I will take a properly designed plastic reflector, with a proper metalized reflective surface, that mechanically fits my flashlight in all aspects, and is very light over a metal one that does not work.

Design of a reflector does not start on the lathe, it starts, at least today, on the computer. That is where you make all your mistakes. At a bare minimum, it starts on a piece of paper tracing rays, but it's rather nasty on paper when all the resources to do it properly with far greater accuracy and flexibility exists on a computer. For prototyping, usually the next step, is a computer controlled lathe. Reflectors need to have rather perfect surfaces.

Silver is of course a good reflector, but as pointed out, you need to use tarnish resistant silver which generally is not inexpensive. The problem with silver is of course cost, but also weight. Aluminum reflects more than good enough for a reflector, but scratches very easy unless coated which is another process. Unlike the silver though, it will not degrade quickly. 

I would suggest a path of progress to read as much as you can on reflector design and skim the threads for preferred beam profiles than work back from there.


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## DrafterDan (Jul 19, 2017)

nothing wrong with a discussion to spark ideas


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## Ozythemandias (Jul 20, 2017)

I'm enjoying this thread and hope it continues, for what that's worth.


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## EseriesModder (Nov 28, 2017)

There isn't supposed to be a right answer, I don't think. When you ask these questions you create discussions and you draw out anecdotes of individual instances where reflectors work in an especially useful way for their form factor, and then that helps you find examples that are worth looking at. Those examples are products that should evolve, and thats all I'm looking for. I don't care if you know how to design a reflector or not. I never imagined I did. Sorry if I offended Ssanasisredna.

I don't think you can say "it starts" anywhere, because some people are going to skip the computer step (or before that the paper step) and jump straight onto the lathe, or dapping block, or vacuum die, or what have you. Thats obviously not how I would advise doing anything, I'm just saying.

Proprietary products, like a specific company's flashlight or other electronic device, need that much thought to evolve, but common objects, like cooking utensils or flashlights in general, evolve regardless simply because of the sheer number of them hitting the market.

Some of them inevitable land on useful improvements regardless of how little thought was involved. That might have been someone making a knock-off of something else, it doesn't matter, but as long as it works and gets incorporated into some future version of that object then the consumer still wins. I'm a consumer, so I appreciate that, even if that makes me a little simple minded.


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## EseriesModder (Nov 28, 2017)

I also gotta say... Aluminum needs to be coated with something to make a good reflector. Bare it will oxidize and wont reflect well. Look at old aluminum hardware, they're dull grey. That's their natural oxidized state. Silver will be fine until it tarnishes, you're correct, but it doesn't "degrade" quickly.

Highly polishing metal will decrease the surface grain, improving the metals environmental resistance a bit. Besides polishing you can plate a smooth surface on. That's why some dental tools are chromed. Also because smooth surfaces are less sticky, but thats also part of why they don't tarnish as quickly as rough surfaces. Anyway.

Tarnish resistant metals aren't expensive either. They're practically the same price, and that increase depends mostly on availability of the form you're looking for(wire, sheet, casting grain, etc). People mostly want sterling silver, so companies that mix proprietary alloys of silver are always trying to encourage people to try them.

Sorry. I just wanted to add that for anyone who actually cares.


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