What would the ideal reflector look like to you?

EseriesModder

Newly Enlightened
Joined
Mar 6, 2017
Messages
29
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.
 
Last edited:

gadget_lover

Flashaholic
Joined
Oct 7, 2003
Messages
7,148
Location
Near Silicon Valley (too near)
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
 

EseriesModder

Newly Enlightened
Joined
Mar 6, 2017
Messages
29
"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.
 

KITROBASKIN

Flashlight Enthusiast
Joined
Mar 28, 2013
Messages
5,489
Location
New Mexico, USA
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?
 

EseriesModder

Newly Enlightened
Joined
Mar 6, 2017
Messages
29
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.
 

gadget_lover

Flashaholic
Joined
Oct 7, 2003
Messages
7,148
Location
Near Silicon Valley (too near)
"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.
 

EseriesModder

Newly Enlightened
Joined
Mar 6, 2017
Messages
29
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.
 

gadget_lover

Flashaholic
Joined
Oct 7, 2003
Messages
7,148
Location
Near Silicon Valley (too near)
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.
 

degarb

Flashlight Enthusiast
Joined
Oct 27, 2007
Messages
2,036
Location
Akron, Ohio
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 lumen@2watts 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.
 

degarb

Flashlight Enthusiast
Joined
Oct 27, 2007
Messages
2,036
Location
Akron, Ohio
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.
 
Last edited:

EseriesModder

Newly Enlightened
Joined
Mar 6, 2017
Messages
29
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.
 
Last edited:

EseriesModder

Newly Enlightened
Joined
Mar 6, 2017
Messages
29
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.
 

degarb

Flashlight Enthusiast
Joined
Oct 27, 2007
Messages
2,036
Location
Akron, Ohio
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.
 
Last edited:

EseriesModder

Newly Enlightened
Joined
Mar 6, 2017
Messages
29
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.
 

PeterH

Newly Enlightened
Joined
Aug 31, 2010
Messages
52
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.
 
Top