Please recommend an android lux/ lightmeter app

I would like to do a runtime/ output test of a lantern. I plan to place it into a white spackle bucket, and take periodic measurements.

Which app, would you recommend?

I have been looking for one as well but then discovered my Samsung tab 4 doesn't have a light sensor

I'm using "Light Sensor", seems to work ok; certainly no frills.
It does have a calibration function but I don't have a way to take advantage of that. :shrug:

I use Easy Light Meter.

It's also hardware dependent. You'll have to try a few.

I use a raspberry Pi and a $6 light sensor from adafruit. Previously I used a Nokia n900. Still do actually

Tac Gunner said:

I have been looking for one as well but then discovered my Samsung tab 4 doesn't have a light sensor

Click to expand...

Hmmm, that doesn't sound right. The Tab-4 has a two cameras (front & rear), correct? If so, it has to have a light (exposure) meter of some kind. As mentioned, you might have to try a few to find one that works.

I have a few installed that work great (Samsung Note 4):

1. Light Meter V2.3 (Borce Trajkovski). This is a nice app, and one of the few (only?) that I've come across that measures color temperature as well. It has the most calibration options of any I've found too.
2. Light Meter V1.2 (Keuwlsoft). This one is pretty cool as it has a real-time graph function, as well as min/max/avg. readings, which are very useful.
3. Lux Meter V1.2 ((Not Quite Them). This is a very simple lux meter with a large display that is a lot easier to read than the previous two at distance. It also has a min/max feature.

:thumbsup:

Can anyone recommend a good light meter for iOS (iPhone)?

Preferably for free.


Thanks!

freefly said:

Hmmm, that doesn't sound right. The Tab-4 has a two cameras (front & rear), correct? If so, it has to have a light (exposure) meter of some kind. As mentioned, you might have to try a few to find one that works.

Click to expand...

There's two types. Some makes use of the ambient light sensor. This is the better option as the sensor generally gives you a straight lux value. The bad is that IR can affect the lux value as generally the sensors measures IR as well. That value needs to be then adjusted for the "green" visible light in software. Some sensors also are not linear.

The other method is via the camera and spot weighting and other calculated methods. It's a reasonable fall back if that's all you got. Better once calibrated.

1. Light Meter V2.3 (Borce Trajkovski). This is a nice app, and one of the few (only?) that I've come across that measures color temperature as well. It has the most calibration options of any I've found too.

Click to expand...

It also supports some hardware sensors too. I tend to try this one first on my phones. Not sure about versions but it supports froyo (2.2) in the one I got.

Froyo? Wow!

That was a goody. The Borce Trajkovski app is updated to work on the most recent os, lollipop.
It uses the front of my phone (the selfie lens) to read.

Kestrel said:

I'm using "Light Sensor", seems to work ok; certainly no frills.
It does have a calibration function but I don't have a way to take advantage of that. :shrug:

Click to expand...

Gentlemen:
THanks for the suggestions.
I had a hard time installing any apps, because my phone was full!

I had to learn how to move some of the stuff on it to my SD card.
FINALLY I got it to work, and I played with it a bit, It looks like the "Light Sensor" app will do the trick.

I had previously installed

Light Meter V1.2 (Keuwlsoft). This one is pretty cool as it has a real-time graph function, as well as min/max/avg. readings, which are very useful.

Click to expand...

I didn't understand the guage, and my readings were a bit erratic, (that was my fault). It would be cool if the graph setting could be changed to take a sampling every so many minutes, rather than milli seconds.

Oh well!

Thanks again...
I'll let you know how I make out.
:thumbsup:

freefly said:

Hmmm, that doesn't sound right. The Tab-4 has a two cameras (front & rear), correct? If so, it has to have a light (exposure) meter of some kind. As mentioned, you might have to try a few to find one that works.

I have a few installed that work great (Samsung Note 4):

1. Light Meter V2.3 (Borce Trajkovski). This is a nice app, and one of the few (only?) that I've come across that measures color temperature as well. It has the most calibration options of any I've found too.
2. Light Meter V1.2 (Keuwlsoft). This one is pretty cool as it has a real-time graph function, as well as min/max/avg. readings, which are very useful.
3. Lux Meter V1.2 ((Not Quite Them). This is a very simple lux meter with a large display that is a lot easier to read than the previous two at distance. It also has a min/max feature.

:thumbsup:

Click to expand...

I will try those, I'm not sure which ones I have tried but I know I downloaded about 5 and all of them said not compatible with device when I opened the app.

IOS user here.

I find that if I place my iPhone 6s on the table with the screen facing up and use the front facing camera on a table, that I can move the phone around a bit to get maximum light readings. If I turn the phone over and use the rear camera, I get a totally different reading.

Front facing camera is 5 mega pixels and the rear camera is 12 mega pixels.

I get different results also using an iPhone 4 between the front and rear camera

My photographic light meters, two Gossen Ultra Pro and a Gossen Mavolux all track within a few lux of one another.

A word to anyone using a hand held lux meter. If you get readings that don't appear correct, (someone else has reviewed the light and you get different readings), change the battery in your meter.

Mr Floppy said:

There's two types. Some makes use of the ambient light sensor. This is the better option as the sensor generally gives you a straight lux value. The bad is that IR can affect the lux value as generally the sensors measures IR as well. That value needs to be then adjusted for the "green" visible light in software. Some sensors also are not linear.

The other method is via the camera and spot weighting and other calculated methods. It's a reasonable fall back if that's all you got. Better once calibrated.



It also supports some hardware sensors too. I tend to try this one first on my phones. Not sure about versions but it supports froyo (2.2) in the one I got.

Click to expand...

Good info, thanks!

One other tidbit on the Keuwlsoft Light Meter: If you click the "info" button, it displays what sensor your device has (being used for the app), and all of it's specs.
I am sure it wouldn't be hard to find that info online for any device, but it's nice to have it right there to reference.

Tried all of the ones mentioned by freefly and everyone of them tell my device does not have a light sensor, guess I just have to buy a standalone unit.

Tac Gunner said:

Tried all of the ones mentioned by freefly and everyone of them tell my device does not have a light sensor, guess I just have to buy a standalone unit.

Click to expand...

Lame! Yeah, as Mr. Floppy pointed out, there are 2 types on sensors (duh), and the majority (all?) of the decent light meter apps use the ambient light sensor. Since the Tab 4 has no ambient light sensor, it would appear you are SOL.

The first one I listed actually has a calibration setting/recommendation listed for the Galaxy Tab, so I guess that must be for the later/newer ones. Time to upgrade I guess!

FWIW, I think the Tab S (and probably anything after) has an ambient sensor, as well as an RGB sensor. So, in theory, that would give you the hardware needed for the light and color temp meter apps. Obviously, I'd want to confirm that before shelling out the cash for a new tablet!

freefly said:

Lame! Yeah, as Mr. Floppy pointed out, there are 2 types on sensors (duh), and the majority (all?) of the decent light meter apps use the ambient light sensor. Since the Tab 4 has no ambient light sensor, it would appear you are SOL.

The first one I listed actually has a calibration setting/recommendation listed for the Galaxy Tab, so I guess that must be for the later/newer ones. Time to upgrade I guess!

FWIW, I think the Tab S (and probably anything after) has an ambient sensor, as well as an RGB sensor. So, in theory, that would give you the hardware needed for the light and color temp meter apps. Obviously, I'd want to confirm that before shelling out the cash for a new tablet!

Click to expand...

I think I will just spend 60 bucks for the light sensor for my Ti-Nspire calculator and go with that instead of dumping the money in a new tablet lol. Thanks for the help though

NoNotAgain said:

Front facing camera is 5 mega pixels and the rear camera is 12 mega pixels.

I get different results also using an iPhone 4 between the front and rear camera

Click to expand...

Yes, it's not the megapixels but the ccd used. Both need to be pre calibrated in some way, that's the annoying thing about this method. There's no access to ambient light sensor to get a raw number on the iPhones. Maybe one day, but it may not be that useful. Like in the Nokia n900, the opening to the ALS is recessed or partially obscured. In some situations, it won't give you a reading or a very low reading as it is quite narrow to the sensor.. Some phones have a smoke tinted portion over the ALS.

It's why I'm moving towards this

I ended up getting and trying out "Light Sensor" V 1.2 jayeshcp

I planned to put a lantern into a five gallon Spackle bucket and take readings.
Instead, I found the light sensor on my phone, and aimed it directly at the led, and moved it around to get the highest reading that I could. I think that is how I would get my most consistent readings.

I thought that I would post the readings, and present them as a percentage of the initial.

This particular lantern however has one of those drivers that gradually decreases output, but then if you turn it off and then back on, the output bounces back up.

I don't know how accurate my phone combined with this app is, but it is probably better than just eye-balling it.

Here is what I got over a three hour period.

initially on medium
10,926 lux
30 minutes later, 11,691
30 minutes later yet, 6095

then an hour later
4140 I turned it off and then back on, (which reset the driver) and it went back up to 8145.

Then another hour later...
5202 and then off and on, (which reset the driver) and it went back up to 8944
------------------------------------------------------------
So after resetting the driver at the end of the second hour, and the end of the third hour, there is a difference of about 800. Since at three hours, it is actually higher, rather than lower, I would say that is a range of error of the light sensor, and this particular app. combination. The error may be even greater, as this was only a single sampling.

^^ I agree, it could be the app and/or phone or...
I've seen in a number of cases in flashlight reviews where batteries cause a spike in output well into it's runtime, then begins a steady decline.

Also in the old days using wack-a-lot lights there was an unwritten rule that when the light got real dim turn it off and wait a while. Then upon re-lighting the batteries seemed to have developed a 'second wind' if you will.

bykfixer said:

^^ I agree, it could be the app and/or phone or...
I've seen in a number of cases in flashlight reviews where batteries cause a spike in output well into it's runtime, then begins a steady decline.

Also in the old days using wack-a-lot lights there was an unwritten rule that when the light got real dim turn it off and wait a while. Then upon re-lighting the batteries seemed to have developed a 'second wind' if you will.

Click to expand...

Yes, Energizer and others, when testing the capacity of their batteries for publication, often put them under load for about 5 minutes an hour, for eight hours a day. They spend more time resting than working.

When I did a run-time output test of the 3D Ozark trail lantern I measured the ma draw and estimated the output. In part this is what I found.

EDIT.... at 264 hours it was at about 0.1 lumen
EDIT... 64 hours later it was still at about 0.1 lumen (328 hours)

I'm not a low lumen junkie, and I pulled the plug. I wanted to get to the switch, so I could look at perhaps adding a constant current driver. I found that I can, and ordered one. I'll try to write up the modifications once the parts come in, and I get a chance to play with it.

EDIT: Oh no... after letting the batteries rest for 7 hours, I hooked them back up, and it is putting out about 2 lumens. That's actually plenty for a small room, like a bath-room.

EDIT: Here we are another EIGHT days and nights later, plus 12 hours. An additional 208 hours of light and it is down to about 0.1 lumen. So at this point we are at 532 hours. I'm going to let the batteries rest for the day.

EDIT: I let them rest for 12 hours, and it went back up to about 1 lumen. So here we are another 10 days plus 10 hours for an additional 250 hours. Its at about 0.1 lumen. 782 hours in total so far.

Click to expand...

When I switched this lantern off and back on, I didn't waste any time and allow the batteries to recover. Undoubtedly, the difference was due to the LED driver.

The Rayovac indestructible 2aa does the same thing.
As does the Energizer lights with "Light Fusion Technology" At least the 300 lumen 4-8 AA folding lantern, and the 4 AA pop up lantern.
So it seems to me that it is a widely used method to extend run-times of lanterns, and some flashlights.