Valid for what?
A 10mm lens with 10mm focal length has the same f number as a 1000mm lens with 1000mm focal length, however the 1000mm lens will throw further because the delta of incidence angles is smaller.
I think you guys are forgetting that an LED is not a point source of light, and therefore it is also important to have the optic as far away as possible from the LED (in order to minimize the delta).
@sedstar Not me. I just want to check the accuracy of claimed focal length and show for a given lens size the effect of focal length (and related f number) on the beam projected. As a former calibration tech (metrology) quantifiable data and related testing have a special significance for me.
If you know the significance of the 4:1 ratio in metrology you get a cookie.
The relationship between lens diameter and focal length are in a way (to me anyway) similar to resistance and capacitance in an rc circuit.
FWIW, the first stage of my plan is to use a set diameter lens and a range of focal lengths with the same emitter. The second stage is to use a set focal length and a variety of diameters with the same emitter. Third stage is lenses with the same (or as close as possible ‘f number’. To minimize cost the head tubes will be rolled aluminum flashing sprayed flat black inside. I’m not wealthy so it will take a while to accumulate lenses to illustrate the relationship between lens diameter and focal length and the resulting beam.
You can also download a free ray tracing tool like * OpticalRayTracer Home Page to get a pretty accurate guess as to how the lenses will perform.
That’s assuming the lenses are sold with accurate characteristics in the description. Often these lenses are offered via sites that also offer 5000 mAh 18650s and 30k lumen latticebright powered flashlights. Establishing a baseline for comparison with real dimensions and values should be useful.
The diameter and thickness are pretty accurate, that’s all you need to know to replicate a lens similar in the software.
Playing around with the diameters and focal lengths and stuff you can see why it is better to have larger diameter and longer focal length.
The ray tracer emits all rays from a single point though, so to see the irl divergence you need to place the origin of the rays about 1mm below the x axis (depending on the led) and look at how much divergence the rays have.
The farther the optic is from the LED, the less the rays diverge.
try to appreciate, i spent most of my life relatively uninterested in photography, beyond if i needed to take apicture? i wanted a camera. i was always fascinated by japanese tourist cameras, as we called them in the old analog days… but, as a mechanical curiosity to me only. if you had one? i wanted to touch it, i wanted to play with the focus and be allowed to snap a pic.
i was always at these times, curious of what “the weird controls were”. its unexplainable to a complete camera noob. they would set the shutter and iris control? i was allowed to “play the focus” and snap my few pics.
then came the night vision projects? LMAO. i had to jump INTO this, and unfortunately? i suddenly hada burning NEED to understand as much as i could about the math of optics, if i was to design something, to uncover something. i had to “grok” the entire system in as much mathematical model as i was able to.
to be into night vision though? is to be into focusing flashlights, though. suddenly? i had to learn about “zoomies”. how to mod a regular zoomie into one. how to make it better. which lens to use… i devised strategies, both mathematical and practical hand tuning… to construct 2 lens zoomies. i can make a “true zoom” zoomie.
i can do those things back into camera lenses too… it all related and intertwined.
my background in computer science and mathematics in a former life? allowed me to do this, and in a deeper, fuller way than the guys just building builds…
but, i “See” all this… for lack of no better WORD… “how” i see it… and i know that the f-number relates image brightness, and the same way translates into PROJECTED brightness. i achieved what i set out to try to do, to make a infrared flashlight that put my emitter, same one everyone else was using… to a distance record at that time. i achieved something for myself in my hobby field. i ended up with my very own “build” and i got to name it.
visible flashlights? being here? was at first, just a fluke., i was into this, only cause i needed tobe… but, you know, had to get just one LED visible flashlight, LMAO… caught the bug.
i can mathematically model a second lens onto any lens, thats imaging or zoomie, and pick my f-number and focal length? practically at will… nd its only possible thru math, and an understanding of the importance of what an f number is, and how to use it, design wise.
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look… i am starting to “grok” what YOU mean now? your recent post with the 10/10 and 1000/1000 lenses “both being f1.0” got me seeing a little from your point of view… but… if now YOU can try to see things a little from MY point of view?
a L-O-T of “flashlight people” were wandering into our night vision site? and i gotta tell you, they dont “grok” it completely the way YOU just tried to explain “what you meant”… what do they “know”? what do they take away from what you guys say? this:
1) to SAY the phrase “diameter is alllllll that matters! nyah nyah”
2) they actually believe, naively and incompletely? that we were supposed to choose out lens, to build our next better zoomie? simply by picking any, and i mean A-N-Y… larger diameter lens.
look, i asked the guy that “came to help us out, since we needed help”? i asked him this:
“sir? let me take out 17 different lenses. random focal lengths. all the same diameter. the individual lenses? they have focal lengths, ranging from as low as 10mm FL… up to one thats 1200mm FL… all of them, though, are 60mm in diameter… are you trying to tell us here, that ANY of those lenses, slapped onto our infrared zoomie build? will all work equally as well? just because they are all 60mm diameter? is that what you are saying?”
he said:
“yes, you finally got it!”
==
then someone (one of our “lens whores” as we call them there?) whipped up, for a joke… three impromptu zoomies, you know, workbench temporary slap togethers… all the same emitter, with 3 VERY different FL lenses, and showed him what he was implying we “should do”… when he finally SAW that the CAMERA SENSOR needed a certain S-I-Z-E of focused emitter to fill the screen
he went “oh……” and went very quiet.
all……he…… grokked……
because of HOW it gets stated? was that “bigger diameter is better! focal length is meaningless!” and we took him for, well… somewhat of a moron.
I suppose N-O-W i am seeing that in the flashlight world? ehhh. you just want a really bright light… a super charged emitter… and you place any lens over it. if its a flooder, its a flooder… if its a thrower its thrower… you can get USE out of it, no matter whether its a mule, a mid grade, or a pencil super thrower?
but… in night vision? the size of that projected emitter? better MATCH the camera view. you know what i mean? a flooder is useless, a tiny pencil mean is useless.
that guy had learned NOTHING about making zoomie flashlights? except to repeat the following phrase like a parrot:
“focal length doesnt mean anything…… only diameter has any bearing on anything….”
and honestly? theres a zillion peole running around the internet world, going off half cocked with this idea. it would be so bad, but… they CORRECT everyone having any discussion, as if they are sage wizards. and most of them cant build anything.
i was on a telescope building site? doing my duty for he night vision site, seeing what optics pros i could find and drag onto my site, to help us? i thought surely some telescope builder could helpus maybe, hey, i was trying…
the telescope guys told me about “some moron” who came to their telescope site? telling THEM that for astral photography? they didnt need to “worry” about focal length and f numbers, because… well, they needed to “understand the truth” that only lens diameter “mattered” for pusposes of getting more light thru the telescope system.
so, when i said i was there “seeing if anyone could give me any designideas for a multiple lens flashlight projecty” they eyed me with GREAT SUSPICION, as you can well imagine, their previous meeting with a “flashlight internet guy” having been so moronic. i had to “prove myself” with a few light math post discussions, before anyone wouldtalk with me about my project.
=
i’m not entirely sure, that you guys realize what impression this is leaving in the minds of people with no backgroundin math, in your hobby, trying to learn how you math guys do what you do?
all many of them are learning, is to repeat one single phrase:
focal length does nothing… only diameter makes it pass more light…
===
and they authoritatively are “correcting” people, having some air of grand knowledge…
=
am i making my point, of what i have encountered, better? people with no math to them (and there are many in the world) are learning to repeat the phrase, like a parrot… i think there needs to be SOME more ideas given to them. if you know what i mean?
eh?
i acted, like i acted??? i thought everyone was acing as if the f-number didnt exist and focal lengths were irrelevant.
for ME? controlling the exact projected size of the emitter (degree size, projection) isnt just a flood or throw “what kind of light do i feel like making today” kind of thing…
for a 3x night vision system? i need a specific FL zoomie lens, to fil THAT scope view correctly.
on 5x? i need a different FL
on 9x? i need a different FL
my focal length, on my IR zoomie? completely controls the size of my emitter in my field of view, expressed mainly in radians, and half angles, and projective geometry.
then of course, i want to pump as many amps thru the poor emitter as it will stand my build heatsinking without making magic blue smoke, lol…
in my design world? i dont have the luxury of making whatever “beamshape” i feel like making. so yeah, focal length and f numbers are critical. they are design criteria number one two three and four five and six.
=
are you now seeing things from my perspective? peolpe from flashlight sites were coming in and saying things completely backwards, IE, “bigger focal length makes a bigger emitter!” and we point out thats backwards? “oh well, it doesnt matter anyways! only diameter means anything for more throw!”
the night vision guys, and even the telescope guys on that site? we were all math guys, and we were wondering where these morons were coming from, that understood nothing, except to repeat that one phrase, like a parrot.
This may be of interest to you, my focusing freaks: Focus Tunable Lenses for LED Lighting by Optotune AG
Cheers 
Sedstar,
Sunnranger(you know and most of guys here don’t know) is multiple lenses system illuminator(or flashlight) based on yukon night vision device 3x42, F1.4? (there is also bigger version ).
Plenty of guys on nvforum were comparing it throw to 67 mm aspheric (X searcher and T67) and it had beaten them in terms of throw but they did not take one important variable - they were not all build under same conditions (same driver, same emitter).
So with proper variables(all systems with same driver and same emitter) when we use SR with IR emitter (4715as for example) has spot size somewhere on half way of hotspot on 50 and 67 mm lenses and visually it really seems that it is out throwing 50 mm and very close to 67 mm one because it has ultra clear die projection I never seen in my life. I can’t measure invisible light…
But I’ve also decided to build fet driven xp-g2 s4 2b SR pill to convert it into flashlight and I really expected that it will kill at least 50mm aspheric and that it will be close(performance vise) to 67mm one since nothing in classic aspherical flashlight world has clearer die projection.
Seriously guys you’ve never seen clearer die projection than in mentioned Sunnranger system but when I put it on the lux meter it was total disappointment throwing around 10-20% less than classic 50mm ones :rage: so it has smaller die projection than 50 mm one and yet throwing less…
Now something good is probably happening when we use IR light source(or even red emitter source inside such system) since it seems that it is passing that light through system much better than visible white led light.
My thought is that special NV AR coating on SR lenses is killing white led light transmission by stopping of blue or other important color that needs to be projected through lenses to give best performance…
I want to say that this system has great potential Why? 42mm lenses that should throw close to 67mm lenses size which means more throw in smaller head diameter.
Hi Luminarium !
Luminarium is from my nigh vision site… we are all “zoomie guys: dyed in the wool… we have no choice but to be zoomie guys…
i was already wanting to make a multiple lens zoomie, and while i was arguing with everyone it was possible… look at my equations… (nobody will look at or cares about equations, by the way) so while i am aguing its possible, and its desireable? at the same time, they were all oohing and aahing over the light he is talking about!
i still remember seeing it, and realizing it was a multiple lens zoomie, and one guy said “good god, i was wondering when he would notice it”…
so, while everyone is telling me it wont work, or that its not practical? at the same time,they are all using it !! (kind of ironic)
also… i had gone and was making 2, then 3… and even one 4 lens zoomie setup… trust me, “the lads” on the site? will remember me and my software to perform the math so no one had to solve equations… not one download, but, they will remember me posting about it if nothing else
i was posting pictures and a short movie? showing MY light, with the same emitter? beating larger diameter “single lens” traditional zoomies. i had the same emitter, and either the same or less current driver… it allowed the lower diameter len SYSTEM to “punch above its weight class”
DIAMETER, you run into a wall… you cant get bigger after a certain point in a gun mounted system… which therefore limits you? adding a second lens behind it? i am able to DROP the f-number and change the focal length…
by running the equations at design time? i found i could pick my f-number and focal length of the system? practically at will…
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diameter was NOT the only way to get more moonbats thru the lens… i simply added a lens, which dropped the f-number, and changed the focal length…
i am still the only one on the night vision site? that routinely adds lenses to existing imaging lenses? to change the focal length, and drop the f-number… driving night vision performance UP…
==
i might not still have the distance record? but i should check… even if i dont? i am not sure erveryone realizes my distanceswere achieved? with the OLD oslon emitter, and the wimpy 1A drivers we were limited to at the time… my high distances? were with half powerful emitter and lower amps than what they use today…
smaller diameter lens, less amps, still keeping up with the joneses !
(whos your daddy… smak-smak-smak, whos your daddy… smak-smak-smak)
what great amusement the world gets, out of forcing the software engineer, who SHOULD be just designing prototypes out of cardboard and plastic? what hes good at?
i dont understand the amusement at making the software engineer learn metal fabricating skills, and machining, and now foundry work? because the machinists refuse to build his units that work better.
the designer? should design. when the prototype works better? then the builders should… well… build it!
i dont ask my mechanic to design me a GPS unit, do i? no… its insane.
my plumber wouldnt ask me to fix his toilet, would he? no. insane.
so, why do i have to go thru all this, for a couple years?
i dont know… but i know this…“they” finally ticked off the wrong software engineer this time… heh heh heh
I am almost complete, in a COMPLETE vertical organization strategy, a-la Henry Ford…
1) i am going to go from scrap aluminum? directly to machining stock in a single step. cost savings.
2) i am the machinist and the fabricator? i dont have to pay a machinist 25 dollars an hour for his time. cost savings.
3) i am the electronics guy, i wire and “mod” everything myself. no outside electronics work. cost savings.
4) i always WAS the designer, doing what everyone else says cant work, showing prototypes that DID work better.
when i am almost done, and i finally come home? “clear me a path”, they aint gonna know WHAT hit them, ha ha ha
i have the persistence, usually reserved for only the truly demented, lol…
some of my friends? they think i’ve gon completely mad, i tell you, lol…
all the notebooks of equations? invisible flashlights? machining equipment? now one stops over, i am pouring red hot molten aluminum in my living room? laughing like a madman?
some of them think i have gone stark raving mad…
Sedstar knows well what he is talking about…
Multiple lenses system have potential. I (and a lot of other guys along with Sedstar) have build it and I know what can be achieved…
The most crisp and sharp die projection ever but in my case it is not equally followed by candela or lux performance when I use classic flashlight emitters because of special NV coating issues I have with yukon lenses… They don’t pass certain color of white emitters so performance is lower than it should be. But with IR emitter and NV equipment is clearly seen potential of such system.
Flashlights based on camera lenses or night vision lenses? Achievable!
I think I will try again but this time with some cheap China variable lenses without AR coating.
And I am also the guy who thinks that aspheric after certain size is undesirable… It is individual but to me sweet spot is 50mm aspheric so if I can have 42mm(or even less) multiple lenses system that will throw like lets say 67 mm lenses than that system is worth a try.
If anyone will read what we are talking about it looks like this: 
That should be equivalent to 67mm IR illuminators single aspheric system.
Sedstar
Could you try to form complete sentences or paragraphs please?
It’s hard to read the jumble of text…try to keep it short too, thanks.
Whoever said that only diameter matters is completely wrong.
Both diameter and focal length matter.
Saying only the F number matters is also wrong, because of what I explained with 10mm vs 1000mm
Both diameter and focal length matter independently.
Multi-lens systems are good if you want to collect as many lumens as possible, this flashlight uses a dual lens system to collect nearly 100% of the light into the lens:
The problem with multi-lens setups is that
A) any defects in the lenses get multiplied at every stage, therefore you need extremely high quality lenses or else there will be visual artifacts
B) there is a lens closer to the LED than in a single lens setup, which increases the divergence hence giving the projected spot a “less sharp” or “larger” size.
Ideally, an LED would be a point source of light and it wouldn’t matter how close the optics were to the LED. We would be able to build flashlights with 10mm lenses that would throw just as much as 1000mm lenses.
This is Mjolnir from Vinz right?
This is not multiple lens system; afaik it uses precoolimator lenses only for main beam enlargement. So it is single lens system with added precoolimator to the emitter. But maybe I am wrong?
Sunnranger is triple(or even 4) independent lens system with de-focus to over-focus ability.
Although it has multiple lenses it has clearest die projection ever. This is example with red emitter:
Or this in comparison with classic aspheric beam:
The precollimator is a tiny lens, so yes it is a multi-lens system.
You can see in your image that it is not a clear die projection at all. There is massive red spill around the image, obviously caused by all those stages.
A “clear die projection” would not have that massive red corona round it.
I saw plenty of aspheric beam and used almost every commercial available aspherical flashlights in a world and I can say that Sunnranger has the clearest die projection…
You can’t avoid little reflection from emitter.
This is sunnranger with white emitter:
Although camera can’t catch all sharpness you can see with your eye it should be clear as day to anyone who have dealt with aspherical flashlights that this is the cleareast die projection ever (far better than lets say B158 which also has very nice beam projection).
For me since I also use precoolimators in my aspherical builds; precoolimator is just a way to enlarge main beam projection without lux loss so I never thought about it as dual lens system although technically as U said it really is dual lens system (precoolimator + main lenses).
In sunnranger you can also add precoolimator to emitter and then you would have 4-5 lens system.
The large circle of light is not from “reflection from the emitter” it is caused by the large amount of optical stages, and refraction between the stages.
As I said before, these multi-optic systems give more lumens but also increases the size of the projection.
A single optical stage would not cause that circle of spill light, and would create a smaller projection while collecting less lumens.
If you look at a high quality single-lens projection of a die you will see that it is just as clear as the sunnranger.
Unfortunately I can’t find any specs or product page for the sunnranger?
the sunranger build…
it started life as a regular zoomie. crelant something rings a bell??
someone tried a night vision imaging lens in place of a regular zoomie lens on it? and it kicked @$$ on accident.
they had to fabricate it up at that point. it was just on a lark? next thing you know, it was the “best build” for an infrared illuminator for a while.
since we use infrared emitters for our night vision zoomies, and since it was a night vision camera lens it worked out very well. (the coatings would have been optimized for night vision infrared, and when used with an infrared emitter, well, things lined up well)
PS - should i be watching my spelling as well as my grammar and punctuation? lol…
Yeah, punctuation and grammar helps a lot, especially when there’s so much text.