Ongoing project: reflector testing

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djozz
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Ongoing project: reflector testing

I just finished building a rig for reflector testing.

It consists of 1) a clamp in which a reflector can be clamped in a fixed position of 7 meters from the wall/luxmeter (the longest distance I can cover in my living room), 2) a double constant (within 0.3%) output lightsource at 350mA, bare leds soldered onto a copper pillar: 1x XM-L2 (cool white) of 180 lumen, and 1x dedomed XP-E2 (cool white) of 120 lumen, and 3) an xyz-stage that can position the lightsource in a controlled way in three axis, to easily position the light source in a 'perfect' focus in the reflector.

With this set-up I can measure and compare the throw of any reflector (and lens) using the exact same lightsource and output every time. Only the getting the best focus is a tricky manual thing, I think I will improve on that over time. On an incidental basis I will add measurements to this thread, building the set-up was more fun than actually doing tests Innocent. And I do not have a that extensive collection of reflectors, and some are dusty/scratched/dirty. When data are being collected, I can even give an idea of throw quality: kcd/cm2 front surface area, for any given reflector.

 

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Oct 20th Test of three C8 reflectors of the same dimensions that I had around: an aluminium OP-reflector and an aluminium smooth reflector, both from Fasttech, and a plastic one (came out of a budget flashlight, can't remember which one). All had some dust, and the alu smooth one had a slight deposit in the deep part (not that important for throw) only visible with the led lighted up inside.

 throw with 120 lumen dedomed XP-E2 (kcd)throw with 180 lumen XM-L2 (kcd)
plastic smooth C8 reflector42.75.7
aluminium smooth C8 reflector41.76.3
aluminium OP C8 reflector17.85.7

That plastic reflector works fine, even though you can see while focussing that it is not perfectly round, the amount of reflection may make up for that. And that an OP reflector throws about as well as a smooth one is correct for bigger leds, but it fails to throw with a small led.

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Dec. 28th 2015

I dressed up my reflector test rig tonight (I'm allowed 2 square meter of permanent hobby space in the house, so part of my rigs must be dismantled after each use) and tested the X6 and D80 reflector. Because I wanted to know for these two flashlights in the same category, separated from all other parameters, which reflector in principle was the better thrower: the odds were at the D80: larger diameter, smoother surface finish.

I'm getting quite a good feeling for finding the best focus for each reflector, so with more reflectors tested the numbers are getting pretty accurate. The test leds are a dedomed XP-E2 and domed XM-L2, both cool white, both constant output at 350mA. Throw is measured at 7 meters, numbers were calculated back to kcd. Here you go:

reflectorXP-E2 dedomed at 350mAXM-L2 at 350mAremarks
BLF X6 reflector21.2 kcd3.79 kcd diameter=29mm
Lucky Sun D80 reflector29.4 kcd4.71 kcd diameter=33mm

So indeed the D80 reflector is the better thrower, for the dedomed XP-E2 the throw is 39% more, for the XM-L2 the throw is 24% more. The actual throw from the whole flashlight is dependent on many more things, I just wanted to single out the reflector.

___________________________________________________

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)

Edited by: djozz on 12/28/2015 - 19:43
Itinifni
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Nice work!

It would be interesting to see wall shots at optimum focus compared to just out either way.

I remember a time, when I searched for lights to fit my needs. Now I search for needs to fit my lights.

ToyKeeper
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This should be very interesting as you get more results. Smile

Reflector focusing is difficult, especially when attempting to tighten a bezel without going out of focus.

MRsDNF
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Beauty. Another one to add to the signature in process. Line. This is really good stuff. 

My current and or voltage measurements are only relevent to anything that I measure.

Budget light hobby proudly sponsored by my Mastercard and unknowingly paid for by a hard working wife. 

djozz said "it came with chinese lettering that is chinese to me".

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

FmC
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Very interesting!  Beer

thijsco19
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Could you do a XHP50 (& maybe 70?) and test how the focus will affect the donut/cross shaped-shadow problem?

vēer
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Heh, this looks interesting!
Sub’d.

Kloepper Knife Works
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Looking forward to the results you get. Do you have a fair number of reflectors you plan to test, or is it going to be as they become a priority?

djozz
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Kloepper Knife Works wrote:
Looking forward to the results you get. Do you have a fair number of reflectors you plan to test, or is it going to be as they become a priority?

No, it is completely random. I will try a Courui reflector next and compare it with a dx-reflector of the same diameter. And I will do some small reflectors as well. I really would like to test some reflectors from high end flashlights as well, but I do not have many, and the few I have are inside a light that I can not/do not want to open for it.

I'm really curious about the kcd/cm2 number, how constant is that or will it differ with quality and/or size of the reflector

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)

djozz
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added data of the Eagle Eye X6 reflector and the Lucky Sun D80 reflector to the OP.

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)

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Are the reflector diameter measurements the OD or ID?

My current and or voltage measurements are only relevent to anything that I measure.

Budget light hobby proudly sponsored by my Mastercard and unknowingly paid for by a hard working wife. 

djozz said "it came with chinese lettering that is chinese to me".

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

viperbart
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Very informative stuff! Thank you so much!

djozz
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MRsDNF wrote:

Are the reflector diameter measurements the OD or ID?

I give the diameter that is actually in use and relevant for comparisons, so the inner diameter Smile

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)

MRsDNF
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Thanks. With the good reports on the 24mm X5 reflector it would be interesting to see how that compares.

My current and or voltage measurements are only relevent to anything that I measure.

Budget light hobby proudly sponsored by my Mastercard and unknowingly paid for by a hard working wife. 

djozz said "it came with chinese lettering that is chinese to me".

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

zoom zoom
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I have about a dozen convoy S reflectors laying around if you want to pay shipping for them. My guess is you already have more than I do but I figured I'd offer anyway!

djozz
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zoom zoom wrote:

I have about a dozen convoy S reflectors laying around if you want to pay shipping for them. My guess is you already have more than I do but I figured I'd offer anyway!

Thanks for the offer, and I indeed have several types of S-reflectors around. I would like to test many more reflectors, but the availability is not so much limiting but the time and will to do the testing. It is my hobby and with limited time I have sometimes modding a flashlight is just more rewarding (it leaves me with a modded flashlight) than doing a test (it leaves me with a number). I'm only human you know Laughing

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)

The Miller
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This is awesome!

With a small reflector this could also be used to check lenses and coatings out.

djozz
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The Miller wrote:
This is awesome! With a small reflector this could also be used to check lenses and coatings out.

You are correct, but I can use my integrating sphere for that too, and perhaps a bit easier. It just requires the will to do all those tests Innocent

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)