UF-T20 REVIEW

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Ervin Anastasi
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UF-T20 REVIEW

UF-T20 REVIEW

Hi,

Ordered one from Wallbuys, shiping was fast i think from their part but my local postal service seems to slow thing a bit. However the flash now is here with me Smile

Build quality at first look seems good. I have an M2 which is the upper standard in terms of build quality and finish, and T20 is almost there in finish and in build, M2 still I find it superior overall.

!DSC 0318 DSC 0319

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DSC 0324 DSC 0325

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DSC 0332 DSC 0333

DSC 0334

!

The body looks sturdy, and in looks is discrete IMO.

The lens looks impressive it works good, well maybe not that good as I was hoping still acceptable, more on that later.

Probably as you all know already stock its an XML T6 (I believe) and in max should be at 2 A. Unfortunately I cant make reliable measures right now bc my multi meter is not so reliable. Since I like the numbers i made some measurements in throw and at max @1 meter measure ~22K lux . Its not something to wow but not bad either. Tint look neutral to me still have to say that I don’t have seen to many different tint of XML leds. If you want to use for ordinary work than its more than satisfactory in stock condition, for me that bought it just for playing with throw, its not enough.

So let’s go in the sec part of review which is one of the first moods of me actually.

I want to change led and driver so I have paid for some xpe2, xpg2, on cooper and some xre together with some drivers 1.4A 1.7A 2.4A and some nice batteries but of course with my bad lack I have nothing show up till now. So I have to say that this mod is a review in progress.

Still as u know I try too progress with what I have in my disposal, so I took an cheap xpe zoom light with an unknown bin, take it apart got the led and try it with the xml driver. I think its around 1.4A driven now at max but this is a guess not an actual measurement.
Well the total output in lumens go down of course(very visible to the eye) but lux go up.
I was expecting more, still this is what i got:

Around 44k lux @ 1 m in max
Not satisfied, and wanting to make better I added another lens.

Chose one to not make UF way more bigger and making attention to preserve dimension as much as i can i chose one lens as u see in photo. Diameter is 40 mm and almost all is used for projecting light (38 mm real diameter used ) . I get an mini drill and work to make an holder for the lens.


It come out good and i am satisfied by overall look and how strong it is. To protect the lens got this and cut it.

The numbers:
From 44 Klux go up to around 65~70 k lux, but the biggest gain was the shape and the clarity of the projected led. The original one is not so good at the quality of projected image, don’t know i got an not so good lens or just this is the ordinary quality of the lens in the UF-T20.
Still i wanted more so of course go dedoming. Chose gasoline dedoming method, and after 3 or 4 hours of waiting the dome almost fall of. The impatient person in me Silly than took a small wire and push it with caution. Lucky all went good this time.


Put back in flash and its alive. Tint go yellow little bit (I like it personally) and measuring lux go: 110 Klux @ 1 m

Waiting for good parts to come (If they don’t lose somewhere!) for now its impossible to improve more .

some more photos:

second mod => http://budgetlightforum.com/node/30274

some of my actual experiments and reviews:
UF-T20 review and mod —->http://budgetlightforum.com/node/30186#node-30186
My EBRZM, over 1 million cd thrower—-> http://budgetlightforum.com/node/30274#node-30274
Ervin’s try (2nd. Annual BLF Scratch Made L

Edited by: Ervin Anastasi on 04/19/2014 - 07:15
ChibiM
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Good job there!

from 40 to 110.. not bad!

djozz
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The reason that the stock lens is so thick is that it can sit close to the led and catch a lot of the light, and still able to focus the led . You used a thinner lens that neccessarily is further from the led, so it catches much less of the light. That does not affect the brightness of the spot (that brightness is almost entirely dependent on the lens diamer, altering the focal length does not affect throw) , but it does make the spot smaller. It all depends on what the goal is, with this lens you end up with a very neat led-die projection and equally good throw, but also with a tiny hotspot.

link to djozz tests 

“I used to think that top environmental problems were biodiversity loss, ecosystem collapse and climate change. I thought that thirty years of good science could address these problems. I was wrong. The top environmental problems are selfishness, greed and apathy, and to deal with these we need a cultural and spiritual transformation. And we scientists don’t know how to do that.”   (Gus Speth)

jerryg
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Interested in what results the new parts will do. Interesting

jerryg

sedstar
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QUOTE:“The reason that the stock lens is so thick is that it can sit close to the led and catch a lot of the light, and still able to focus the led . You used a thinner lens that neccessarily is further from the led, so it catches much less of the light. That does not affect the brightness of the spot (that brightness is almost entirely dependent on the lens diamer, altering the focal length does not affect throw) , but it does make the spot smaller. It all depends on what the goal is, with this lens you end up with a very neat led-die projection and equally good throw, but also with a tiny hotspot.

MY CURIOSITY…

I keep HEARING that, basically put, “focal length does nothing, diameter is everything”

why then, operating on this logic… does not everyone simply use WIDE lenses, and have extremely short focal lengths… why, you should det 5mm FL lens, set it real close to the emitter… and be done.

after all, focal length does nothing.

=======================================================================

i’m not being mean, i’m only being facetious, and using an exaggerated example to demonstrate my point.

====================================================================

maybe my experiences with IR emitters (oslon 4715S) is a radically different sort of light than the visible you guys all use, and it reacts radically different?

since IR is largely invisible, AND we dont have meters to measure stuff and post numbers… a certain one or two camera sensors are what we use… and every one of us, either buys or builds an IR light, mostly lensed throwers.

while the human eye can be “fooled”… we are watching a SCREEN the camera sensor is feeding to… our main figure of merit, in lieu of meters and readings? How far away can you SEE the scene? how far away can you SEE the stuffed animal on the screen?

low focal lengths just dont “throw” enough that we can SEE anything on the screen, at distance… I got my best distance with increased focal length.

i think I realize what you guys MEAN when you all say “higher focal length is not BRIGHTER !!! its the same BRIGHTNESS!!! only beam shape has been changed!!!”

but… how FAR away can i show of a picture of that stuffed bunny rabbit on my night vision screen?

it may not BE brighter, in reality or mathematically? But… the higher focal length sure shows up on the SCREEN being brighter…

(and FL being EQUAL, yes, wider diameter is definitely an improvement)

==================================================================

maybe i dont understand exactly what is meant by “throw” being (or not being) “increased”… to ME and MY application? nothing else matters, except whether i can watch a coyote or a wild pig, at 300m or 400m… and 400m is better. To me, thats more “throw”.

i kinda skip over the kilo-candela and mega-lux meter numbers, and just look for the “beamshots”, lol…

====================================================================

I mean, i KNOW what is MEANT when you guys say “it has not increased in brightness!! the longer focal length only altered beamshape!! its actually less brighter, cause its further away from the emitter!! only a wider lens can increase brightness!!!”

but, knowing that, and i understand it… but, when i look at my SCREEN, and the image got “brighter”… and can now see the trees behind the stuffed animal… not just a dim outline of th animal?

in a basic level… brightness has increased.

With enough black coffee and cigarettes? all things are possible…

I am currently still shipping… REAL GENUINE CREE xp-g emitters, the classic… brace yourself? as low as 20 cents apiece!! Check out the SALES THREAD, everyone is happy… then PM me

SALES THREAD:
http://budgetlightforum.com/node/52528

if you are into reloading? this is my site… I inherited the remains of what was once arguably the best reloading site on the internet… its the “BLF” of reloading sites…

http://reloadbench.freeforums.net/

if you think night vision would be cool? It IS… this site i am a member of, and its basically the “BLF” of home made scratch-built digital night vision. They are at the leading forefront of advanced DIY for digital night vision, and thats gun mounted or handheld… builds rival and exceed commercial offerings…

http://nightvisionforumuk.com/

Ervin Anastasi
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ChibiM wrote:

Good job there!

from 40 to 110.. not bad!

Thank you Smile yes its interesting but don’t forget from stock is around 20K Smile

I am going further playing around with what i have yesterday I hit around 800 K lux. my aim is to go over 1 million lux but for that I have to wait. for my new setup i think to make another thread because i think its not fair to call the new flash light just a UF-20 Smile

some photos Silly

distance in sec photo around 170 m

djozz wrote:

The reason that the stock lens is so thick is that it can sit close to the led and catch a lot of the light, and still able to focus the led . You used a thinner lens that neccessarily is further from the led, so it catches much less of the light. That does not affect the brightness of the spot (that brightness is almost entirely dependent on the lens diamer, altering the focal length does not affect throw) , but it does make the spot smaller. It all depends on what the goal is, with this lens you end up with a very neat led-die projection and equally good throw, but also with a tiny hotspot.

you are right and wrong this time sry. I get more lux more than 50% and you can be sure about that. how it is possible? simply by the gain i made on diameter alone. it may look strange but the only thing that matters in throw is diameter of the reflector or lens in my case, and of course the brightness of the source in my case the xpe led. so believe me on this, that having two different lenses with the same diameter but different focal length (so in other terms one thinner and the other thicker) will not differ at all on throw. so thicker or thinner its not important in throw. so how did I improve in result you may ask? I gain in used diameter of the lens. the original lens is using only 33 mm in diameter despite being a bigger lens in reality. I design my new lens system with care taking attention that wasted space to be as small as possible. the real diameter of my lens is ~40 the effective one used in throw ~38~39. from 33 to 38 may not sound much but pay attention, what count is the real area of the lens A = Pi*r^2 =3.14*r *r so in the original lens we have an A = 854.87mm^2 in my new design A=1163.57 mm^2
conclusion:
if we look carefully to the numbers what we see? a small difference in diameter i just ~0.14(14%) gave us back a difference 0.306(31%) (almost double in this case) in area(and of course because of the r*r factor we don’t have a linear correlation here) !!!
in practice i should see 0.3 or 30% gain in lux (so in throw) what i see are around 0.4(40%) ~0.5(50%) this because the original lens i got its not so good and have some loses. still a good example when theory meet practice i must say Smile

to not make it more complicated, i do not count here the factor that I am using both lenses in the same time but this do not interfere absolutely in throw. than why I am using those both? because I gain in total lumen that way, but this is another discussion hahaha…. (so in my case that spot its not that smaller Wink )

so yes you are right in throw only diameter count and the thickness do not make an difference indeed, but in my case you are wrong because relatively with the same diameter of the flashlight head, i gain around 50% throw simply by engineering little better and making it little more expensive Silly

some of my actual experiments and reviews:
UF-T20 review and mod —->http://budgetlightforum.com/node/30186#node-30186
My EBRZM, over 1 million cd thrower—-> http://budgetlightforum.com/node/30274#node-30274
Ervin’s try (2nd. Annual BLF Scratch Made L

kevind43
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sedstar wrote:
QUOTE:“The reason that the stock lens is so thick is that it can sit close to the led and catch a lot of the light, and still able to focus the led . You used a thinner lens that neccessarily is further from the led, so it catches much less of the light. That does not affect the brightness of the spot (that brightness is almost entirely dependent on the lens diamer, altering the focal length does not affect throw) , but it does make the spot smaller. It all depends on what the goal is, with this lens you end up with a very neat led-die projection and equally good throw, but also with a tiny hotspot.

MY CURIOSITY…

I keep HEARING that, basically put, “focal length does nothing, diameter is everything”

why then, operating on this logic… does not everyone simply use WIDE lenses, and have extremely short focal lengths… why, you should det 5mm FL lens, set it real close to the emitter… and be done.

after all, focal length does nothing.

=======================================================================

i’m not being mean, i’m only being facetious, and using an exaggerated example to demonstrate my point.

====================================================================

maybe my experiences with IR emitters (oslon 4715S) is a radically different sort of light than the visible you guys all use, and it reacts radically different?

since IR is largely invisible, AND we dont have meters to measure stuff and post numbers… a certain one or two camera sensors are what we use… and every one of us, either buys or builds an IR light, mostly lensed throwers.

while the human eye can be “fooled”… we are watching a SCREEN the camera sensor is feeding to… our main figure of merit, in lieu of meters and readings? How far away can you SEE the scene? how far away can you SEE the stuffed animal on the screen?

low focal lengths just dont “throw” enough that we can SEE anything on the screen, at distance… I got my best distance with increased focal length.

i think I realize what you guys MEAN when you all say “higher focal length is not BRIGHTER !!! its the same BRIGHTNESS!!! only beam shape has been changed!!!”

but… how FAR away can i show of a picture of that stuffed bunny rabbit on my night vision screen?

it may not BE brighter, in reality or mathematically? But… the higher focal length sure shows up on the SCREEN being brighter…

(and FL being EQUAL, yes, wider diameter is definitely an improvement)

==================================================================

maybe i dont understand exactly what is meant by “throw” being (or not being) “increased”… to ME and MY application? nothing else matters, except whether i can watch a coyote or a wild pig, at 300m or 400m… and 400m is better. To me, thats more “throw”.

i kinda skip over the kilo-candela and mega-lux meter numbers, and just look for the “beamshots”, lol…

====================================================================

I mean, i KNOW what is MEANT when you guys say “it has not increased in brightness!! the longer focal length only altered beamshape!! its actually less brighter, cause its further away from the emitter!! only a wider lens can increase brightness!!!”

but, knowing that, and i understand it… but, when i look at my SCREEN, and the image got “brighter”… and can now see the trees behind the stuffed animal… not just a dim outline of th animal?

in a basic level… brightness has increased.

What we mean by “throw” is beam distance see this http://lux.yi.org/throw/

Part of the problem is, it’s not a linear relationship. You need four times the light to get twice the beam distance. Which is part of the reason why, what seem like big gains in candela, aren’t percieved as brighter by the human eye.

We do have tools that can measure IR intensity, they are very expensive but they do exist. IR light is measured in different units than visible light. These guys have ‘em http://www.intl-lighttech.com and http://www.grlabs.com/ will build you one too for about $600-800. The light meter is the only quantitative way to measure output of a given light. What you are talking about is percieved brightness. I believe there is a member on NVUKforum that has one. before I called it quits I was working with GRlabs to build me a meter.

Lux and Lumens are photopic units weighted based on the response curve of the human eye. The human eye is not sensitive to infrared, therefore you cannot define a lumen for infrared wavelengths.

However, you can define infrared incident energy in radiometric terms such as power per area, e.g. W/m^2. There are instruments that can measure incident infrared energy as well, but you have to be careful in defining the wavelength band you’re interested in, and the expected energy levels.

Read more: http://www.physicsforums.com

There are huge differences that factor into perceived brightness. Some of them are but not limited to, in your application, is LCD screen, camera, scope, IR lightsource, human eyesight.

human eyesight alone has remarkable differences from person to person. Namely pupil size as we age. As we age our pupils dialate less and less. So, the exit pupil on your scope you use has a huge influence on light transmittance to the eye.

As I am sure you know, the scope you choose makes a big difference. There is a big difference in quality glass and quality coatings from scope to scope.

When you add lenses to a system you lose light transmittance. Bottom line, add lenses lose efficiency. To see a good example of this just watch Roland’s videos comparing scoped vs scopeless digital NV tests. The only difference is the number of lenses the camera has to “look” through.

Part of what makes the T20 so good as a hunting light is the beam angle. The beam angle of the T20 with an XPE/XPE2/osram 4715s is such that it closely matches the field of view of most scopes. Thus eliminating the “black” ring you see when using a large long focal length lens. I don’t know if you have looked through a scope with an illuminator with a 66mm lens or larger but the beam angle is so small that the die image projected is smaller than the field of view of the scope creating a black ring in the scope. If you have ever hunted with a light like this you will find it very difficult to reacquire your target if you lose it in the “Black” ring. And you also have to “aim” the beam to center it in the field of view. Which only works at a specific distance. Lets say you have the light with 66mm lens mounted above the scope and have the beam centered in your field of view at 300 yds, and a pig or coyote walks out at 200 yds, won’t be able to see it! Which is one of the reasons I never marketed the 66mm or larger builds. That said the throw of the larger lenses is enough that if the hunter is hunting fairly still targets, the larger lens systems have a huge advantage.

One of the reason’s you are seeing better results with short focal length lenses is the center thickness of the glass. Thin glass transmits more light than thick glass.

I had a hunter in OHIO, using one of Rolands’ scopeless systems and my T20 ID and kill a coyote at 420 yds! That’s hard to do in daylight! And I have killed coyotes at 300 yds using a T20 with RED emitter. Keep in mind that my red T20’s put out over 24,000Cd. And my red T66’s are approaching 80Kcd.

A large lens has the ability to gather and focus more light into a tighter spot than a smaller lens, increasing throw.

example: XPE2//sinkpad/1.4A…..32mm lens(T20) 24KCd same set-up…………….66mm lens(T13w/66mm) 75Kcd

The IR light behaves about the same whether behind a reflector or lens as the visible LED’s. The 4715s and the xpe2 are about the same die size, so the projected image is about the same size. I have built many aspheric and reflector type lights both IR and visible RED and GREEN emitters.

What I would really like to see is a IR or color emitter with the die size of an sst-90 or XM-l then we could use larger lenses with better results.

all this said can you see farther/better or not?

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I really like your initial pic’s, for someone who’s never handled a UF-T20 before and thinking about building one that’s very helpful to see all the parts like that. I wish there was more reviews of different lights with pic’s of them broken down to their individual components. I know that would have kept me from being disappointed at least a few times.

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sedstar
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hey… that comment about “my buddy… coyote… 420 yards”… that jogged my memory banks! That was probably YOU that posted that on the night vision forum.

its me… SEDstar… I use the same screen name anywhere i go.

(I’m the guy on the night vision site that made the first “futon” build and named it, lol)

=======================================================

counter point: diameter cant be “everything”… on that logic, no lensed IR illuminator using less than 40mm diameter lens should be able to “keep up” with larger diameter lens illumnators… i have pictures of illumination 100, 150 meters… with three-quarter inch diameter lenses!!

would you really expect to see ANYTHING at 100m to 150m with a 3/4” lens on your oslon? (less than one inch in diameter…)

my “big” illuminator build, has under 40mm clear diameter on the main objective lens…

===================================================

i keep wondering what improvement will be made with my “system” when i try the same setup out with 66 or 78mm diameter main objective lens on my illuminator, instead of the sub-40mm diameter lens i use for a main objective now… i dont DOUBT the theory, I have been sort of “handicapping” my illuminator build style with comparatively small diameter lenses.

I have illuminated well at 400m, with a scoped setup… my scopeless goes up to twice as far.

its not like my scoped setup is using anything wonderful, its a hopelessly ordinary gun scope… its not like i am not using the same oslon emitter everyone else is… same cam as everyone else too, ej230 is the only one i got… i use the one J230 cam in both my scoped and my scopeless builds…

the only difference that could account for my distances i am getting? that i can determine? the only difference would be… how i set my lenses up.

i mean, i guess its possible i got some super duper oslon emitter no one else got? but, i doubt it…

With enough black coffee and cigarettes? all things are possible…

I am currently still shipping… REAL GENUINE CREE xp-g emitters, the classic… brace yourself? as low as 20 cents apiece!! Check out the SALES THREAD, everyone is happy… then PM me

SALES THREAD:
http://budgetlightforum.com/node/52528

if you are into reloading? this is my site… I inherited the remains of what was once arguably the best reloading site on the internet… its the “BLF” of reloading sites…

http://reloadbench.freeforums.net/

if you think night vision would be cool? It IS… this site i am a member of, and its basically the “BLF” of home made scratch-built digital night vision. They are at the leading forefront of advanced DIY for digital night vision, and thats gun mounted or handheld… builds rival and exceed commercial offerings…

http://nightvisionforumuk.com/

light junkie
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DayLighter wrote:
I used a 4” diameter magnifying glass lens glued to 6” long acrylic tubes to act as a giant zoomie.
with this set up I can throw a lot further, at 1 meter it measures over 580K :D( stock light)
580 dauuuummmm

Lj

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Yeah ,hey sedders , I don’t post much anymore or build as many lights. My new job is very demanding and stressful , leaves very little time or energy for lights. I am still working with Roland on a few projects.

Bigger is definitely better when we talk about lenses/reflectors and throw, the trade off is laser-like pencil beam.

I think another area that should be explored is AR coatings. I think substantial gains can be made with aspheric light builds. Having lenses coated to perform well with the given wavelength emitter being used 625nm(red), 850nm, 940nm is crazy expensive.

I just got an AR coated lens to try in a dereelight night master build that has a red Cree xpe2. I will post the results when done. I am not very optimistic , however, I have purchased dozens of lenses in the last couple years and very few work out the way intended.

I definitely need to get a meter to measure the gains/losses with IR light.

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djozz wrote:

That does not affect the brightness of the spot (that brightness is almost entirely dependent on the lens diamer, altering the focal length does not affect throw)

Strictly the brightness (at small angles) will scale with average intensity*lens coverage angle^2*focal length^2. In terms of lens diameter, the problem is that intensity is not uniform across the lens as it is a function of the emitted angle. Even assuming that the intensity was uniform per angle (which it is not), the relationship of the lens radius to the coverage angle from centre is not 1:1, but tan(angle). In other words it’s always less than 1:1, except at tiny angles.

The brightness will scale (at most) with arctan(radius)^2, so it’s difficult to know the change with lens radius, but unlike focal length it is not squared. The brightness will always be slightly reduced in some way when using a lens with the same diameter and shorter focal length. In reality you also have to take into account the non-uniform Lambertian intensity which peaks at the centre. There is some balance to be found in what focal length produces useful throw.

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islisis wrote:
djozz wrote:

That does not affect the brightness of the spot (that brightness is almost entirely dependent on the lens diamer, altering the focal length does not affect throw)

Strictly the brightness will scale with average flux*lens coverage angle*focal length. In terms of lens diameter, the problem is that flux is not uniform across the lens as it is a function of the emitted angle. Even assuming that the flux was uniform per angle (which it is not), the relationship between the lens radius to the coverage angle is not 1:1, but tan(angle). In other words it's always less than 1:1, except at tiny angles. The brightness will scale with arctan(radius), so it's difficult to know the change with lens radius, but unlike focal length it is not 1:1. The brightness will always be slightly reduced in some way when using a lens with the same diameter and shorter focal length. In reality you also have to take into account the non-uniform Lambertian flux which peaks at the centre. There is some balance to be found in what focal length produces useful throw.

Thanks islisis, I had not thought yet of the effect of reduced intensity of the light at an angle, and the other effects, that made me think it all over again (which is a nice thing Smile ). What also may reduce the brightness at shorter focal length is increased reflection on the underside of the lens because the angles are increased.

link to djozz tests 

“I used to think that top environmental problems were biodiversity loss, ecosystem collapse and climate change. I thought that thirty years of good science could address these problems. I was wrong. The top environmental problems are selfishness, greed and apathy, and to deal with these we need a cultural and spiritual transformation. And we scientists don’t know how to do that.”   (Gus Speth)

islisis
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np, it’s good to think of these problems in context. It’s not hard to understand but I like thinking of how to explain. I have edited the post’s language far too many times already cos I hate causing confusion :/

Ervin Anastasi
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thanks all for the inputs, all appreciated. unfortunately do not have much time to respond all one by one but just to quick read. will find some time, hope sooner than later.
the review is a review in progress so I am trying to complete and polish as much as I can with photos schematics and measurements. still wating for parts.
second mod is almost finished, will open a new thread and put the link here as soon as I can.
I am open to all other mods so if you have something interesting please share here, photos and measurements will be more than wellcome. comparisons are allways a good thing and helpful.

some of my actual experiments and reviews:
UF-T20 review and mod —->http://budgetlightforum.com/node/30186#node-30186
My EBRZM, over 1 million cd thrower—-> http://budgetlightforum.com/node/30274#node-30274
Ervin’s try (2nd. Annual BLF Scratch Made L

ImA4Wheelr
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Nice review and mod.  Glad you joined BLF.

Ervin Anastasi
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finally i have some new shiny little parts with me now Smile have started work, some pics are on the way some numbers too, still some work to do too to finish like I hope.

sedstar as easy as is seems in first sight as hard can become some times to think about how light bend Smile I suggest(if I may) that you experiment in visible spectrum of light. it will be easier for you than, to see,measure and come in conclusions about your experiments and projects. than after that i believe it will be a safe bet that changing the source to infra will not alter the results.
As kevind43 said brightens is little bit tricky when it come to perception by the human eye, because eye can adapt in very wide range in different situations, but experimenting and measuring in visible spectrum is more easy nevertheless. plus light meters are very easy to use and to get.

wish you luck in your projects!

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kevind43 wrote:
Yeah ,hey sedders , I don’t post much anymore or build as many lights. My new job is very demanding and stressful , leaves very little time or energy for lights. I am still working with Roland on a few projects.

Bigger is definitely better when we talk about lenses/reflectors and throw, the trade off is laser-like pencil beam.

*I think another area that should be explored is AR coatings. I think substantial gains can be made with aspheric light builds. Having lenses coated to perform well with the given wavelength emitter being used 625nm(red), 850nm, 940nm is crazy expensive.
*
I just got an AR coated lens to try in a dereelight night master build that has a red Cree xpe2. I will post the results when done. I am not very optimistic , however, I have purchased dozens of lenses in the last couple years and very few work out the way intended.

I definitely need to get a meter to measure the gains/losses with IR light.

my second lens is coated. its an quality lens I got form a dead projector….
I think its good that its coated and maybe improve little bit still i don’t believe it make a huge difference at least in my case. maybe when the lens sits very close to the source can make more difference because theoretically should reflect back less light, but i haven’t tried that yet.

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islisis wrote:
djozz wrote:

That does not affect the brightness of the spot (that brightness is almost entirely dependent on the lens diamer, altering the focal length does not affect throw)

Strictly the brightness will scale with average intensity*lens coverage angle*focal length. In terms of lens diameter, the problem is that intensity is not uniform across the lens as it is a function of the emitted angle. Even assuming that the intensity was uniform per angle (which it is not), the relationship of the lens radius to the coverage angle from centre is not 1:1, but tan(angle). In other words it’s always less than 1:1, except at tiny angles.

The brightness will scale with arctan(radius), so it’s difficult to know the change with lens radius, but unlike focal length it is not 1:1. The brightness will always be slightly reduced in some way when using a lens with the same diameter and shorter focal length. In reality you also have to take into account the non-uniform Lambertian intensity which peaks at the centre. There is some balance to be found in what focal length produces useful throw.

well i would love to go in details here, because i think its an interesting arguments, buts its frustrating for me to express myself well enough(and explaining this will need to be long enough) because I don’t know very well English. however as soon as I read your comment one experiment crossed in my mind so…

I just make this quick enough

, do not have a caliber right now but its around 22mm in diameter(inner circle).
I put it in front of my modified UFT20 and measured. the result are:
1. UFT20 @3.15 m ~670 lux (dimater of the lens around ~38mm)
2. UFT20 modified lens +22 mm ring @3.15 m ~237 lux
3. UFT20 original lens +22 mm ring @3.15 m ~235 lux

anyone is free to duplicate and or interpret those results and what this means Wink
and some new photos:

, still measuring but with dome i get ~105Kcd at start(that beam is around 800 Kcd!!!) but it goes quick down after that… hm it seems i have a huge amount of work with managing of heat . why it have to be so hard Silly still work is going on Smile
what i wanted to stress here is that i really like effect of the ray of light with dome. its hard to explain with words but its a lovely bluish tint and for some reasons it looks strong. when dedome the lux go up (the light is there the meter see it) but the ray of light lose some of this bluish aura. :/ I think the particles in the air reflect more the blue spectrum…

some of my actual experiments and reviews:
UF-T20 review and mod —->http://budgetlightforum.com/node/30186#node-30186
My EBRZM, over 1 million cd thrower—-> http://budgetlightforum.com/node/30274#node-30274
Ervin’s try (2nd. Annual BLF Scratch Made L

sedstar
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cool build and review!

With enough black coffee and cigarettes? all things are possible…

I am currently still shipping… REAL GENUINE CREE xp-g emitters, the classic… brace yourself? as low as 20 cents apiece!! Check out the SALES THREAD, everyone is happy… then PM me

SALES THREAD:
http://budgetlightforum.com/node/52528

if you are into reloading? this is my site… I inherited the remains of what was once arguably the best reloading site on the internet… its the “BLF” of reloading sites…

http://reloadbench.freeforums.net/

if you think night vision would be cool? It IS… this site i am a member of, and its basically the “BLF” of home made scratch-built digital night vision. They are at the leading forefront of advanced DIY for digital night vision, and thats gun mounted or handheld… builds rival and exceed commercial offerings…

http://nightvisionforumuk.com/

Ervin Anastasi
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thermal management done Silly I could follow soldering MBCP on pill way and probably would have one of the best heat management possible but I wanted that despite having a good heat management also have the flexibility to easy experiment later. also i want to have the led centered as much as possible so chose the hard way. after reading god know how much on heat dispersion, cree led construction and so on, finally is over.

working with pill take me the biggest amount of time:

its sanded with 1200 flint-paper and it come almost mirror finish. small touches are here and there too, do not want to go too much in details for now Silly

the end result is this (for now bc i have to add something later ):

!IMG 20140421 095710 IMG 20140421 095757

IMG 20140421 095843 IMG 20140421 095923

IMG 20140421 101012 IMG 20140421 144815

!

what maters is that the led hardly surpass 50 grade Celsius in max and output is very very stable, with slight reduction from cold start(till both pill and mas of body is saturated … ).

some numbers:

with dome on(want to finish all work and than go dedome! )

in max 2.4 A (but i suspect its a little more because Vf was 3.6 ) it throw 104K cd Smile in max with original lens (without my optical mod) ~68 Kcd

i make some work with light collar but even that only with collar i manage to get 40 % more light punting it at work with lenses was a total failure. in the pics above one is with collar. i find a way to make it work somehow but the flashlight dimensions grow to much, lumens go down way too much and the spot was very small. working with collar need some serious equipment.

well next step is dedome, some cosmetic here and there and its done Silly

some beam shots(all my photos are from my phone) one is from actual third mod that with dome is around 700K cd and is looking in good shape to go over 1M cd soon Silly
the other is my moded UF-T20 100K cd but with dome on:

!2014 04 18 23 01 43 Night IMG 20140421 013809edit

!

some of my actual experiments and reviews:
UF-T20 review and mod —->http://budgetlightforum.com/node/30186#node-30186
My EBRZM, over 1 million cd thrower—-> http://budgetlightforum.com/node/30274#node-30274
Ervin’s try (2nd. Annual BLF Scratch Made L

islisis
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Ervin Anastasi wrote:

well i would love to go in details here, because i think its an interesting arguments, buts its frustrating for me to express myself well enough(and explaining this will need to be long enough) because I don’t know very well English. however as soon as I read your comment one experiment crossed in my mind so…

Sorry, originally I was thinking of the problem in terms of a diameter:focal length ratio argument to try and keep the discussion simple and in the end botched the general expression I showed :/
brightness is proportional to (1-cos(angle))*focal length^2, which I simplified as (angle*focal length)^2 without thinking… only also leaving out the ^2 which i’ll edit (again :/) now
i took the partial differential with respect to focal length and plotted them, and they are both positive with a maximum gain followed by drop to zero at infinity… so for a constant diameter there is always some slight gain in brightness with longer focal length
anyway the bigger and more complicated factor will of course be the non-uniform Lambertian intensity
Ervin Anastasi
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@*islisis* interesting, I didn’t thought before how to prove theoretically/mathematically but it sound like you are in the right track at first look. unfortunately i forgot to make partial differentials, because are more that 15 years that don’t exercise on math. If i find some time will open my books and will try to do it myself just for fun if i can. pretty sure some math software will make it very easy.

In practice there is like 0 difference or like ~2% from what I measure, but that can also be part off human mistakes or tolerances in light meter or other variables.

pretty much my sec mod on UF-T20 is done.

from around ~100K cd with dome on de-domed now is ~180K cd I would love to manage to put some kind of small light collector inside but with tools I have is almost mission impossible. still I am looking around for some random object that can be suitable for the task Big Smile just some small gain like ~30% will be perfect Silly

about dedoming I almost never manage to double lux, but max ~80% is this normal?

waiting night for some beam shots.

meantime i make yesterday some photos:


" onmouseover="this.src=' '" onmouseout="this.src=' '" />

ok I give up for today trying to learn mouse over thing (no more free time at my disposal for today):p

ah forgot, distance to the trees is ~80m

some of my actual experiments and reviews:
UF-T20 review and mod —->http://budgetlightforum.com/node/30186#node-30186
My EBRZM, over 1 million cd thrower—-> http://budgetlightforum.com/node/30274#node-30274
Ervin’s try (2nd. Annual BLF Scratch Made L

islisis
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congrats on the dedome =D

i tried to rely on intuition arguments and didn’t research the problem at all but i came across a random thread with a link to this explanation: “as the focal length is reduced, the beam divergence increases at a greater rate than the total beam power”. that might be easier to understand…

try a free software: wxmaxima

this is what it gives me for the relative brightness vs x=focal length/diameter

compare with ‘geometric factor’ from the site mentioned above (logarithmic):

Fritz t. Cat
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I got my T20, in spite of the pictures, partly because it was well liked on another thread here and partly because I thought I might be able to use the lens in my Yezl T-9. The build quality really is good, perhaps the only better build I have is a C8. I like the brass pill, trapezoidal anodized threads, etc. But it is pug ugly and feels just as bad in the hand, so I don’t want to use it as a regular white light.
Instead, I took its lens and put it into the Yezl, put the DX lens that didn’t quite fit in the Yezl in the T20 and put my deep red led into the T20. The pill cutouts for driver and star were nearly right and it is functionally excellent. It works well in that role.

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。