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HermannSW
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Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Wed May 30, 2018 6:28 pm

I used a 5000lm led with 50W LED driver a lot for very high framerate (>700fps) raspiraw videos, because those videos where just dark when lit with 1000lm or below.

This is the set of 50W driver and 50W led I bought, currently special deal of 6.99$ in total:
https://www.aliexpress.com/item/High-Po ... 77294.html


Today I received two spare 50W leds I ordered after much very good experience with the one I had. After I tested each separately, I decided to test to power the two new leds with the single 50W led driver I have. I placed the two leds back-to-back, so that + and - where on same side, and connected the led driver cables to both. To my surprise both leds did shine very bright (since I have no cooling I can only power the leds for some seconds, but that is sufficient for taking very high framerate videos of closing mouse trap or yo-yo action, since /dev/shm available memory restricts video to less than 16s in length).

Some questions:
1) is 50W led driver used capable of driving 2 (or even 3) 50W leds?
2) if yes, will I get 10000lm(15000lm) light then?
3) how can I verify this? (light measurement somehow, or current measurement?)

Find the technical specs of driver and led further below.

This was test setup with led driver driving 2 leds at once
(for me much brighter than the photo shows):
Image


This is 50W led driver data
(Input, AC:85-265V, 50/60Hz -- Output, DC:20-38V, DC:1500mA±5%, 50W):
Image


This is 50W led data (I have 3 "cold white" type leds):
Image
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

gordon77
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Wed May 30, 2018 7:41 pm

I guess it all depends on what the driver is really capable of, if only 50w then you can't get 100w out of it. I would guess the volts are dropping.

To check for twice the brightness put the camera in manual and take a picture which 2 different settings, for 2 leds you should he able to half the exposure time or the ISO used for 1 led. Then compare the 2 pictures, they should show the same brightness.

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Imperf3kt
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Wed May 30, 2018 8:04 pm

5000 lumens is VERY bright, which your image does not look. It doesn't even look like 1000lm.
How are you focusing the light? emitting 5000lm is not the same as shining 5000lm on a surface.
55:55:44:44:4C
52:4C:52:42:41

Rose tinted glasses are difficult to see through.

ethanol100
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Wed May 30, 2018 11:32 pm

This is a constant current led driver. It will try to increase the voltage until the current reaches 1500mA. It can only go up to 38V -> the constant current can't be reached.
You would need a driver which could supply at least 60-64V for two or 90-96V for 3 led modules(LEDs connected in series).

I would only use one led module per driver. Normally you would use a lower current to increase the LEDs life time.

Do you put the leds in series or parallel? If parallel the current will be split to 750mA each, which should result in the same overall 50W(each at 25W).

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 3:24 pm

Imperf3kt wrote:
Wed May 30, 2018 8:04 pm
5000 lumens is VERY bright, which your image does not look. It doesn't even look like 1000lm.
How are you focusing the light? emitting 5000lm is not the same as shining 5000lm on a surface.
I had to wait with my smartphone to adapt some seconds because otherwise I would have got an all white photo. As I said the scene was much brighter for me than the photo shows.
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 3:34 pm

ethanol100 wrote:
Wed May 30, 2018 11:32 pm
This is a constant current led driver. It will try to increase the voltage until the current reaches 1500mA. It can only go up to 38V -> the constant current can't be reached.
You would need a driver which could supply at least 60-64V for two or 90-96V for 3 led modules(LEDs connected in series).
That is what I expected since the led driver is sold for one led, and good for one.
I would only use one led module per driver. Normally you would use a lower current to increase the LEDs life time.
That was not my intent, wanted to know whether I can get more than 5000lm with that LED driver.
Do you put the leds in series or parallel?
Parallel intentionally, I once did serially by accident one time and both modules did only glow a bit.
If parallel the current will be split to 750mA each, which should result in the same overall 50W(each at 25W).
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 3:45 pm

gordon77 wrote:
Wed May 30, 2018 7:41 pm
I guess it all depends on what the driver is really capable of, if only 50w then you can't get 100w out of it. I would guess the volts are dropping.
As said I expected that, perhaps a bit more than 5000lm, but definitely not 10000lm because it is only a 50W led driver.
To check for twice the brightness put the camera in manual and take a picture which 2 different settings, for 2 leds you should he able to half the exposure time or the ISO used for 1 led. Then compare the 2 pictures, they should show the same brightness.
That sounds interesting experiment. I mostly used raspivid and raspiraw sofar for high framerate video capturing. Only seldom raspistill.

Do you mean to use raspistill?
How do I "put the camera in manual"?
I know about exposure, no experience with ISO.
Do you have sample command lines for taking the photos for comparison?

I did connect all three led modules in parallel to the one led driver I have. It works and is very bright, but by ethanol100's explanation it seems that although all three leds are active, only 5000lm in total should be there.

Here is photo of another smart phone camera of setup with 3 leds in parallel, I had to wait until the smart phone camera adapted to very bright scene (some seconds) before being able to take the photo. It is another smart phone camera, and here all three leds are in same direction, whereas in previous photo both leds showed into different directions. Anyways this photo looks much brighter than the previous:
Image



This is the setup when powered off:
Image
Last edited by HermannSW on Thu May 31, 2018 3:56 pm, edited 1 time in total.
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

gordon77
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 4:26 pm

Try

Raspistill -o image.jpg -ex off -ss 20000 -ISO 100

Vary ss value

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 6:49 pm

Hmm, these are my first experiments with raspistill.

I made number of 5000lm leds powered adjustable from 1-3 with breadboard.
Image


For below two photos scene was lit by single 5000lm led, v2 night vision camera with 20° lens.

Code: Select all

raspistill -o 20000.100.jpg -ex off -ss 20000 -ISO 100
results in black image (although preview on HDMI monitor during capturing showed scene):
Image


It seems to be "-ex off" that is responsible, without

Code: Select all

raspistill -o 20000.100.nexoff.jpg -ss 20000 -ISO 100
results in this image, shutter time needs to be much lower than 20ms for 5000lm:
Image
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

gordon77
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 6:56 pm

You need ex off for manual. Keep reducing ss and see if you get an image.

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 7:03 pm

gordon77 wrote:
Thu May 31, 2018 6:56 pm
You need ex off for manual. Keep reducing ss and see if you get an image.
With "-ex off" I only get black images, what can be the reason?
What can be countermeasure (reducing shutter time would make it even darker)?
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

ethanol100
Posts: 667
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 7:48 pm

try:

Code: Select all

raspistill -o 20000.jpg -ss 20000 -ag 1 -dg 1
setting the analog and digital gain to 1.

You can use

Code: Select all

raspistill -t  30000 -o test.jpg -set
strings test.jpg | grep gain

This will just try to set a good value for shutter speed and gains. You can then take these values as a stating point.
exp=XXX ag=YYY where XXX is the exposure in musec and YYY/256 is the analog gain.

See viewtopic.php?t=156754#p1022554 how gains are set for iso values.

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Thu May 31, 2018 8:49 pm

Thank you for the guidance, first feedback for now.
ethanol100 wrote:
Thu May 31, 2018 7:48 pm
try:

Code: Select all

raspistill -o 20000.jpg -ss 20000 -ag 1 -dg 1
setting the analog and digital gain to 1.
results in this image:
Image

You can use

Code: Select all

raspistill -t  30000 -o test.jpg -set
strings test.jpg | grep gain

This will just try to set a good value for shutter speed and gains. You can then take these values as a stating point.
exp=XXX ag=YYY where XXX is the exposure in musec and YYY/256 is the analog gain.

See viewtopic.php?t=156754#p1022554 how gains are set for iso values.
I did those two commands, this is the result with one 5000lm led powered:

Code: Select all

pi@raspberrypi3Bplus:~ $ strings test.jpg | grep gain
ev=-1 mlux=-1 exp=2618 ag=256 focus=255 gain_r=1.230 gain_b=2.035 greenness=-28 ccm=6022,-2314,394,-936,4728,310,300,-4324,8126,0,0,0 md=0 tg=272 272 oth=0 0 b=0 f=272 272 fi=0 ISP Build Date: Apr 16 2018, 18:20:48 VC_BUILD_ID_VERSION: af8084725947aa2c7314172068f79dad9be1c8b4 (clean) VC_BUILD_ID_USER: dc4 VC_BUILD_ID_BRANCH: HEAD 
pi@raspberrypi3Bplus:~ $ 
This is the result with two 5000lm leds powered:

Code: Select all

pi@raspberrypi3Bplus:~ $ strings test.jpg | grep gain
ev=-1 mlux=-1 exp=2467 ag=256 focus=255 gain_r=1.207 gain_b=2.031 greenness=-33 ccm=6022,-2314,394,-936,4728,310,300,-4324,8126,0,0,0 md=0 tg=275 275 oth=0 0 b=0 f=275 275 fi=0 ISP Build Date: Apr 16 2018, 18:20:48 VC_BUILD_ID_VERSION: af8084725947aa2c7314172068f79dad9be1c8b4 (clean) VC_BUILD_ID_USER: dc4 VC_BUILD_ID_BRANCH: HEAD 
pi@raspberrypi3Bplus:~ $ 

And this is the result with three 5000lm leds powered:

Code: Select all

pi@raspberrypi3Bplus:~ $ strings test.jpg | grep gain
ev=-1 mlux=-1 exp=2354 ag=256 focus=255 gain_r=1.265 gain_b=1.828 greenness=-43 ccm=6022,-2314,394,-936,4728,310,300,-4324,8126,0,0,0 md=0 tg=268 268 oth=0 0 b=0 f=268 268 fi=0 ISP Build Date: Apr 16 2018, 18:20:48 VC_BUILD_ID_VERSION: af8084725947aa2c7314172068f79dad9be1c8b4 (clean) VC_BUILD_ID_USER: dc4 VC_BUILD_ID_BRANCH: HEAD 
pi@raspberrypi3Bplus:~ $ 

Below is test.jpg from run with three leds powered.
Is it correct that two leds powered shows a little bit more total luminosity than one, and three more than two because of decreasing exposure values: 2618 / 2467 / 2354 ?
Another question: 1.5A*38V=57W, more than one led can consume. But 0.75A*38V=28.5W can be consumed by one led of two in parallel, and another 28.5W by the other. Shouldn't total luminosity be 57/50=1.14 times more with two powered leds compared to only one?
Image
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Tue Jul 03, 2018 7:21 pm

I did order a 100W led driver and received it recently, in order to test with 5000/10000/15000 lm:
Image


Today I build test environment, v2 camera capturing scene for 30 seconds with -set option, 100W led driver connected to two 5000lm LEDs in parallel and 50W led driver connected to third 5000lm LED:
Image


I did capture theses commands (after waiting LEDs to cool down in between because I don't have any heat sinks in place):

Code: Select all

pi@raspberrypi3Bplus:~ $ raspistill -t  30000 -o test.15000.jpg -set
mmal: Exposure now 2448, analog gain 256/256, digital gain 1580/256
mmal: AWB R=350/256, B=347/256
mmal: Exposure now 2448, analog gain 256/256, digital gain 1436/256
...
...
mmal: AWB R=410/256, B=384/256
mmal: Exposure now 406, analog gain 263/256, digital gain 256/256
mmal: AWB R=409/256, B=383/256
pi@raspberrypi3Bplus:~ $

I am a bit confused on the exposures determined, I would have awaited roughly X, X/2 and X/3 for some X for 5000/10000/15000 lumen. But I see 860/747/406?!?!?
When back at home I will have to insert ampmeters into the setup to measure how many amps are used.
Currently it seems that turning on all three only does a little bit more than double the total lumens (if lumens are reciprocal related to exposure determined with "-set" option).

Code: Select all

pi@raspberrypi3Bplus:~ $ strings test.5000.jpg | grep gain
ev=-1 mlux=-1 exp=860 ag=259 focus=255 gain_r=1.574 gain_b=1.421 greenness=-30 ccm=6366,-1522,-744,-1806,7272,-1368,244,-2814,6672,0,0,0 md=0 tg=296 296 oth=0 0 b=0 f=296 296 fi=0 ISP Build Date: Apr 16 2018, 18:20:48 VC_BUILD_ID_VERSION: af8084725947aa2c7314172068f79dad9be1c8b4 (clean) VC_BUILD_ID_USER: dc4 VC_BUILD_ID_BRANCH: HEAD 
pi@raspberrypi3Bplus:~ $

Code: Select all

pi@raspberrypi3Bplus:~ $ strings test.10000.jpg | grep gain
ev=-1 mlux=-1 exp=747 ag=260 focus=255 gain_r=1.593 gain_b=1.582 greenness=-8 ccm=6226,-1322,-804,-1890,7282,-1294,200,-2820,6722,0,0,0 md=0 tg=302 302 oth=0 0 b=0 f=302 302 fi=0 ISP Build Date: Apr 16 2018, 18:20:48 VC_BUILD_ID_VERSION: af8084725947aa2c7314172068f79dad9be1c8b4 (clean) VC_BUILD_ID_USER: dc4 VC_BUILD_ID_BRANCH: HEAD 
pi@raspberrypi3Bplus:~ $

Code: Select all

pi@raspberrypi3Bplus:~ $ strings test.15000.jpg | grep gain
ev=-1 mlux=-1 exp=406 ag=263 focus=255 gain_r=1.597 gain_b=1.496 greenness=-17 ccm=6334,-1468,-766,-1834,7294,-1360,232,-2806,6676,0,0,0 md=0 tg=287 287 oth=0 0 b=0 f=287 287 fi=0 ISP Build Date: Apr 16 2018, 18:20:48 VC_BUILD_ID_VERSION: af8084725947aa2c7314172068f79dad9be1c8b4 (clean) VC_BUILD_ID_USER: dc4 VC_BUILD_ID_BRANCH: HEAD 
pi@raspberrypi3Bplus:~ $

This is test.15000.jpg:
Image


Hmm, that looked strange, so here are the other two images taken. test.5000.jpg looks as I would expect:
Image


But test.10000.jpg stripes seem to indicate bad led driver quality ...:
Image


Can this be visual representation of German powerline frequency of 50Hz?
3280x2464 images get captured at 15fps with raspivid, what can be said about single frame capture time of raspistill?


P.S:
The 50W+100W exposure value can be explained from the other two:

Code: Select all

$ echo "(860+747)/2/2" | bc -ql
401.75000000000000000000
$ 
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Is 5000lm+5000lm leds = 10000lm with this 50W driver?

Mon Feb 11, 2019 4:44 pm

Imperf3kt wrote:
Wed May 30, 2018 8:04 pm
How are you focusing the light? emitting 5000lm is not the same as shining 5000lm on a surface.
Thanks for that comment, it resolved my issues in this new thread:
https://www.raspberrypi.org/forums/view ... 4#p1428384

A symmetrical design with aluminum foil on cardboard inner walls was focus enough as the measurements in that posting showed. With my three 50W led drivers I can now enable 5000lm, 10000lm and 15000lm(!) very very bright light, this is view from bottom:
Image
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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