Anyone with a luxmater who want's to share their measurements...

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Budgeteer
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Anyone with a luxmater who want's to share their measurements...

It's friday! I do not work on saturdays and sundays so it's free time!

I decided to pull my luxmeter out of drawer and start to use it.

I did some measurements and anyone who wants is kindly asked to post their info for the sake of comparing the results. Nothing really alot meaningfull but it can be fun.

Later on i have to build myself something along the line of an "integrating sphere" for trying measuring lumens.

 

Test method:

Floor setup of luxmeter, fresh battery, measure tape offsetted by luxmeter height from floor level and exactly 1 metere from the flashlight lens (give or take a very few mm of the margin of error).

Fully charged hi-max 18650 li-ion for li-ion capable flashlights/dropins

10 seconds reading trying to catch a best possible readout on the luxmeter.

the luxmeter itself (photo stolen from net from somewhere):

http://image.made-in-china.com/4f0j00FMqtUkdKLYrJ/Digital-Lux-Meter-LX-1020BS.jpg

My candidates and their respective readings:

Q5 based Ultrafire C3 SS on max with AA Eneloop - 2112 lux

R2 based uniquefire hs-801 on max: 33400 lux

R5 XTAR D01 diving flashlight on max:  13300 lux

R5 p60 dropin 5mode (MF) SMO reflector at high: 8390 lux

XM-L p60 dropin 3mode H-M-L (MF) SMO reflector at high: 5390 lux

Q5 p60 dropin 1mode at max (DX) OP reflector: 7920 lux

 

Now i'm interested how similar results can be had considering the cheap luxmeters accuracy, emiiters, reflectors, lenses, drivers, exact distance can all affect measurements.

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

Edited by: Budgeteer on 03/11/2011 - 13:32
Hrvoje
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Nice luxmeter. I figured out that I got more real results when I measure at the distance of 2 meters, and then multiple the value with 4.

Budgeteer
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Out of curiosity how do you know the real value?

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

Don
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Inverse square law - double the distance, quarter the output. But it is easier to detect the peak brightness in a larger hotspot.

At 3 metres the result will be 1/9 of the one metre value

4 metres: 1/16

 

and so on.

 

This also prevents saturating the meter's sensor.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Budgeteer
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Sigh... so i best redo the test with 2 or 3m and calculate the readings?

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

Don
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Not really necessary but it should give better results.

 

Just to add to the fun you should be measuring from the emitter, not the lens. I use 1 metre measurements as the underside of my desk is exactly one metre from the floor - it is easy to line up the emitter with the bottom of the desk.

Small errors in positioning are much less important when the distance is larger, but I don't have a 2m high desk.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Budgeteer
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Eeeew!

I sell a luxmeter cheap! anyone?

Joking aside, good info... one never stops to learn.

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

Aleister
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I 'd love to take part to this experiment this weekend but my lux meter should be on my hands on Monday (HKP says). So I will try to follow next week.

Let a flooder be my wife and a thrower be my mistress

Don
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I can give anyone who wants edit rights to the lights spreadsheet where we can put up our measurements. If everyone has a tab of their own, we can sort out variations between measurements where we have the same lights to compare.

 

Or I can take the results from here and put them up on a tab in the sheet in my sigline. Whatever is easier for people.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Budgeteer
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Nice idea.

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

photon1k
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Don wrote:

I can give anyone who wants edit rights to the lights spreadsheet where we can put up our measurements. If everyone has a tab of their own, we can sort out variations between measurements where we have the same lights to compare.

 

That's a great idea Don. You've just motivated me to get an inexpensive meter and start playing this game. Any recommendations on a meter?

Don
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Mine is certainly not a lab-grade device but it was affordable. I got this one

http://www.dealextreme.com/p/50000lux-2-1-lcd-digital-light-meter-20170

 

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Aleister
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Quicky:

Lux            Flashlight

15000        Aurora SH-40 SST-50 (pleasant surprise, body looks like KD C8 but it has a deeper smooth reflector and perfect beam)
10200        MF XML Dropin
8500          KD C8 (xml) - 18650
8000          Aurora AK-P7
6500          KD XML Dropin (it has a donut hole which makes it very hard to measure, in reality it is a good dropin)
4000          iTP A1 eos (r2) - 16340
3000          Palight SS (xpg) - 18650 (compact)
550            iTP A3 eos upgraded (q5) - alcaline (old - used alcaline)

14000         edi-t (p4) - 18650 (FTT zoomed in)
14000         edi-t t11 - 16340 (FTT zoomed in)
13000         lichao lc-007a (q5) - 18650 (FTT zoomed in)
8800           romisen rc-c6 (FTT zoomed in)

Lux meter: http://www.dealextreme.com/p/digital-lux-meter-with-stand-200000lux-5100

Numbers are somewhat rounded as I am playing for the first time with a lux meter and this play isn't really that scientific.

All measurements are on 1 meter.

 

 

 

 

 

Let a flooder be my wife and a thrower be my mistress