Budget Lumen Measuring Rig

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BROODMASTER
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Budget Lumen Measuring Rig

How would I calculate lumens from lux with this setup?

This is a 68 quart Coleman cooler that is stood up on its' short side and the lid is closed when collecting data. Data collector is a smartphone using the Androsensor app.

I've looked up lux to lumen calculators and formulas but I'm still not sure how to convert to lumens with this.

Thank you for your assistance!

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zak.wilson
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I wrote an app for that… but you’ll still need a source for calibration. The readme talks more about calibration and reducing error with makeshift integrating boxes.

Ceilingbounce – flashlight testing and runtime graphs for Android

BROODMASTER
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zak.wilson wrote:
I wrote "an app":https://github.com/zakwilson/ceilingbounce/releases for that... but you'll still need a source for calibration. The "readme":https://github.com/zakwilson/ceilingbounce/blob/master/README.md talks more about calibration and reducing error with makeshift integrating boxes.

Zak, Thank you for developing the app! I'll look into it. I think I'll use an S2+ or my D4 v.1 at the highest regulated mode for calibration.

Recent/ongoing Mods:

https://imgur.com/a/8qUyZbL

 

https://imgur.com/a/EHq0i

 

                                

 

-X3-
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This is my budget solution :
5$ foam sphere
15$ luxmetre

Calibrate with some known value (at med/low levels) to find your multiplier and you’re good

"-X3-, is there any place in your house without a flashlight ?" 

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kikkoman
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Quote:
Data collector is a smartphone using the Androsensor app.

Some smartphone sensors are highly directional (and all of them are to some degree…) so you need some sort of diffusor directly on top of the sensor.

djozz
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Look up the brand and type of the ambient light sensor in your phone (which is what the app uses as luxmeter). It can be looked up on your phone, there is a list somewhere with phone hardware parameters. They differ hugely in their spectrum response, a bad one can easily cost you 30% in accuracy compared to a good luxmeter, but you may be lucky, some are really good (Texas instruments makes some very good ones) and are within 5%.

BROODMASTER
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-X3- wrote:
This is my budget solution : 5$ foam sphere 15$ luxmetre !{width:80%}https://lh3.googleusercontent.com/_q47RzCcQYSE88czSAy9hQd9tz96Q9DVhm30cn... Calibrate with some known value (at med/low levels) to find your multiplier and you're good

Yes! Much better setup! My wife is giving me funny looks with that cooler setup! Lol

Recent/ongoing Mods:

https://imgur.com/a/8qUyZbL

 

https://imgur.com/a/EHq0i

 

                                

 

BROODMASTER
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X, K & D, Thank you for you recommendations and knowledge share. I spend a little money on nice lights but am too frugal to buy a light meter! I use what's on hand and sometimes, it's the biggest thrill to use that 'thing' I've had for years! It figures well with being on the BLF. And quality is held in high regard!

Recent/ongoing Mods:

https://imgur.com/a/8qUyZbL

 

https://imgur.com/a/EHq0i

 

                                

 

BROODMASTER
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I looked up the approximate value for a D4 v.1 w/Luminus SST20s, at full regulation and at turbo and if I divide the Alcatel Idol 4 sensors' lux reading by 3, ie. 465/3, I get 155 lumens. Not bad.  With a 3.9 V battery, I get right under 3000 lumens on turbo with the same calculation. I'll test a few more lights that I have and have been tested here on BLF. Pretty cool! Thanks!

Recent/ongoing Mods:

https://imgur.com/a/8qUyZbL

 

https://imgur.com/a/EHq0i

 

                                

 

djozz
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BROODMASTER wrote:

I looked up the approximate value for a D4 v.1 w/Luminus SST20s, at full regulation and at turbo and if I divide the Alcatel Idol 4 sensors’ lux reading by 3, ie. 465/3, I get 155 lumens. Not bad.  With a 3.9 V battery, I get right under 3000 lumens on turbo with the same calculation. I’ll test a few more lights that I have and have been tested here on BLF. Pretty cool! Thanks!

Thumbs Up that it works as planned!

Could you look up the brand and type of the ambient light sensor in your phone, for my curiosity?

mrheosuper
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X3 wrote:
This is my budget solution :
5$ foam sphere
15$ luxmetre

Calibrate with some known value (at med/low levels) to find your multiplier and you’re good


is it linear ?, double the lux means double lumen ?

Forgot my pen

djozz
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mrheosuper wrote:
X3 wrote:
This is my budget solution :
5$ foam sphere
15$ luxmetre

Calibrate with some known value (at med/low levels) to find your multiplier and you’re good


is it linear ?, double the lux means double lumen ?

It is lineair, but the lineairity is not device-related, for any set-up good or bad, if nothing else is changed but the light output, your luxmeter will measure twice the value if the output is increased twice, if it does not do that you just have a very bad luxmeter.
mrheosuper
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djozz wrote:
mrheosuper wrote:
X3 wrote:
This is my budget solution :
5$ foam sphere
15$ luxmetre

Calibrate with some known value (at med/low levels) to find your multiplier and you’re good


is it linear ?, double the lux means double lumen ?

It is lineair, but the lineairity is not device-related, for any set-up good or bad, if nothing else is changed but the light output, your luxmeter will measure twice the value if the output is increased twice, if it does not do that you just have a very bad luxmeter.

I see, does the reflector affect the reading?

Forgot my pen

BROODMASTER
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djozz wrote:
BROODMASTER wrote:

Thumbs Up that it works as planned! Could you look up the brand and type of the ambient light sensor in your phone, for my curiosity?

 

I did some searches and found various assemblies/modules but nothing about the ambient light sensor maker & specs. I'll need to attempt various related queries. 

Recent/ongoing Mods:

https://imgur.com/a/8qUyZbL

 

https://imgur.com/a/EHq0i

 

                                

 

-X3-
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mrheosuper wrote:
djozz wrote:
mrheosuper wrote:
X3 wrote:
This is my budget solution :
5$ foam sphere
15$ luxmetre

Calibrate with some known value (at med/low levels) to find your multiplier and you’re good


is it linear ?, double the lux means double lumen ?

It is lineair, but the lineairity is not device-related, for any set-up good or bad, if nothing else is changed but the light output, your luxmeter will measure twice the value if the output is increased twice, if it does not do that you just have a very bad luxmeter.

I see, does the reflector affect the reading?

Nope, it’s the purpose of the integrating sphere.
Of course a really floody (mule) light could have an effect (inflated numbers are to be expected).

"-X3-, is there any place in your house without a flashlight ?" 

My Flashlight public album (mods, emitter swaps, eye candy)

My reviews channel (French language, Olight, Thorfire, Sofirn, Lumintop : 60+ lights tested)

My personal channel (including Olight SR mini, S1, S2, S1A and S-mini disassembly)

M4DM4X blog, saves you $$$