okay… okay… okay! (I am skimming the posts that appeared while i had my 8 or so hour much-needed nap)
Now? I am happy. Now we are cooking with gas!. Now, we have several people attracted, involved and engaged… all of whom are used to looking at basic equations.
a couple basic points i would like to make back?
—- Mr enderman can say whatever he wants to me, it doesnt bother me in ANY way. No ones “feelings” matter the slightest bit as far as to whether i am right or not right.
—- i like the how many potatoes joke back. i’m irish, and i have a sense of humor. good show!
—- what i think is confidence, anyone else could easily take for rude or conceited or arrogant. “semantics”
—- i write clear and concise enough english that all my information is completely conveyed. You keep insisting that perfect punctuation and grammar are what wins mathematical arguments? Let me know how that goes for you.
aha, here we go. Here’s a little gem:
“Maybe sedstar can enlighten us with some of this complex “math” he speaks of, because so far there is no existing proof that a multi-lens setup can get more throw than a single lens of the same max diameter.”
The equation isnt a particularly hard one? Its 8th grade algebra to solve it. It implies and states, among other things? that ANY lens with positive focal length? can be replaced by TWO OTHER LENSES with an airgap, such that the OVERALL focal length is exactly the same.
Necessarily, the rear lens will be CLOSER to the LED… it HAS to collect more light that wasnt lost by the original one lens being so far away. (you keep getting hung up on the idea that the SAME ORIGINAL LENS will then have less focal length? Perfectly true statement. If your original lens was 100mm FL? wonderful… simply choose 2 lenses of 150mm FL, as an example.
placed touching (no airgap)? they form a single lens of 75mm FL (which would seem to support enderman’s “always less” statements) BUT when you introduce the airgap? the focal length begins to RISE UPWARDS and approaches 150mm if you go far enough.
if you STOP increasing the airgap when the system hits 100mm FL? What have you achieved?
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Build number 1? a single positive lens of 100mm FL is used. We ALL know the problem, but i state it anyways. The problem is that at that 100mm distance? a lot of light gets lost and doesnt hit the lens. Since you can only increase diameter to a certain practical extent? Youy are stuck like chuck with a “dance” between higher focal length, and the trade-off loss of lost light from the distance.
Build number 2? TWO lenses of 150mm FL e-a-c-h replace the single lens. At a certain airgap? They “hit” 100mm FL, which was the value of your original lens. The REAR lens is much closer to the LED, its losing less light that was lost. The overall FL is STILL 100mm FL in sum total.
no where did i state that any particular difficult to source lens was needed. ANY of us goes and buys a single 100mm FL lens, dont we? ANY of us can buy instead two 150mm FL lenses to replace the one lens, and have the same FL as we wanted originally, except now with one lens farther back, collecting and not wasting light.
choose the 2 lenses carefully? run the numbers enough? you can put things where you want them, and its always an advantage.
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you want to SEE the math? right out in the open for you? hiding right out in PLAIN SIGHT ?
https://en.wikipedia.org/wiki/Lens\_(optics)
go down the page, down the page… right underneath “chromatic aberrations”? right below that is the “compound lens”. There are the 4 equations. If you sit and play with paper/pencil/calculator long enough? using the example i just used of my 2 lens build replacing the other 1 lens build? you will see it too… you just have to run it with the right airgap to “hit” it…
no ray traces,any 8th grade algebra student can handle it… and those equations? are hundreds of years old i bet,they are LAWS. they do not LIE. Perhaps instructive to note that there is no delta problem here, and CAMERA lenses seem to work in spite of the fact that Mr. Enderman seems hung up on things on his “ray tracing program” which I am glad i dont know about, they would prevent me from using paper and pencil to illustrate what i say.
LOOK, if you are going to use a 60mm diameter, 100mm long TUBE anyways? To have a 60mm diameter lens of 100mm FL anyways? You COULD use two 60mm diameter lenses, each with 150mm FL… and simply put THOSE into the tube. (you have an empty space of 60mm diameter, whats wrong with a second lens back there?)
THEN what Mr enderman seems hung up on, his “always shorter FL” hang-up? works right how you WANT IT to help you, instead of hurt you.
get off the idea of using the SAME lens with some “other” collimating lens behind it… get ONTO the idea of choosing two OTHER lenses that combine with airgap to REPLACE your original single lens.
the math? does not LIE. and? i’m npot the only one saying this.
Dr. JONES kept repeating himself saying it, out of hundreds of people arguing about “throw and beamshape” (meaningless drivel) that arent doing anything constructive? i was the only person that read that thread, and went and found what he was talking about.
THIS is how simple compound camera lenses work, they dont suffer from Mr Endermans “ray tracing perplexing delta issue”, do they? NO, they take pictures just fine.
THIS is why the “sunnranger” lens kicks butt, and has 4 lenses. THIS is why it has a higher FL than suggested by its short length.
THIS is what Dr Jones on CPF showed a picture of in the long trainwreck thread on his bench.
THIS is what the violin teacher thread someone posted the build is made from.
THIS is what they describe as “step two” in EDMUND OPTICS math white paper on “prototyping illumination systems”. step 1, is a single lens… step 2? two lenses, and the advantages!
https://www.edmundoptics.com/globalassets/resources/articles/prototyping-illumination-systems-with-stock-optical-components-en.pdf
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its not just ME? all the experts are saying it.
people build this way. The engineers at edmunds optics, curiously dont describe the ray tracing delta paradox… i say? throw your ray tracing program away, its tell you something you dont need…