Smartphone light meter apps

[cfl...KING]

Which one of any is the most accurate? Ones that only require your phone not buy attachments ect

 

[Ca++]

Not all phones are created equally. Using different sensors, and operating systems.
Other than that, they are all pretty much the same. Separated by user bias, more than results.
This top search result lists the best 7

The Best Light Meter Apps in 2024 (7 Picks)

Grab a light meter app and make your life easier. We share our top Android and iOS picks. Accurately set the exposure for photos and videos.

www.photoworkout.com

Note that the top 4 are ios and the next 3 android. I have no doubt they are apple users doing this review.

Some time ago it became evident that some phones needed a jail break to measure past 50,000lux. The stock software wasn't interested in values beyond this, as it had already maxed out the screen brightness.
Newer phones aimed at replacing cameras, might do better. Though by that suggestion, they should come with the app as standard

 

[goingrey]

Not all phones are created equally. Using different sensors, and operating systems.

Are there some kind of calibration functions and are they reasonably easy to use on these apps?

 

[Ca++]

Are there some kind of calibration functions and are they reasonably easy to use on these apps?

Yes, the one's I looked at still need telling the colour temperature of the light they are measuring. Which gives an idea just how unpolished these apps are. These phones have cameras, so should be able to see the white balance themselves.
Typically they get the lux reading within 10% though, which isn't terrible.

 

[goingrey]

Yes, the one's I looked at still need telling the colour temperature of the light they are measuring. Which gives an idea just how unpolished these apps are. These phones have cameras, so should be able to see the white balance themselves.
Typically they get the lux reading within 10% though, which isn't terrible.

Yeah seems reasonable, especially if it is consistent and not fluctuating 10% either way.

 

[Hiddenjems]

The Photone app an an iPhone is always within 5 percent or so of our quantum meters. It’s the facial recognition camera with ir and other wavelength sensitivity.

 

[UGDoCV]

The Photone app an an iPhone is always within 5 percent or so of our quantum meters. It’s the facial recognition camera with ir and other wavelength sensitivity.

I use this app on android. Gives me all info I need for now.

 

[NIKT]

Are there some kind of calibration functions and are they reasonably easy to use on these apps?

In my opinion, this type of programs are worth very little.
Even if it is possible to calibrate at some point.
Comparison with a lux meter of quite good quality for class B equipment.

Calibration at a point under the light source in relation to the lux meter readings. Then try to measure on the grid. The effect is spot on and yes, it holds well. Apart from that, differences of up to 30% - the further from the light source, the worse.

I don't know to what extent this is due to a completely unknown and probably very large angular error of the smartphone camera, and to what extent it is due to, for example, very different indication errors on the phone depending on the light intensity.

=>
angular error of the measuring head. on the right on the left adaptation of the response to the photopic curve. From the documentation of a class A lux meter. In the case of a smartphone camera, the head cuts off a lot of light coming at sharp angles. And adapting the response to the photopic curve is probably programmatic and sufficient for assessing luminance when taking photos.

=>

I also played with one of the first versions of the photone program when you didn't have to pay anything for it.

In my opinion, this program is nothing more than an "overlay" for the lux meter that multiplies the lux result by the coefficient.

For most white LED sources, a completely reasonable but very inaccurate conversion factor is 0.015. You can even combine knowing the spectral temperature of LED and CRI or SPD in the case of practically white sources for plants and simply take measurements with a good lux meter. And then multiply the obtained values by a factor closer to the real conversion factor into photon flux in the "PAR" or ePAR range.

According to my completely private opinion, measurements taken with a smartphone with an application can be used to improve your mood or have fun. I have no idea what mistakes this could make. Maybe 10% in one case, maybe 30% in another.

This uses something used to take photos to measure brightness, and in this case it is good enough.

There's even an old comparative article somewhere: I'll give you the link in a moment - perhaps phones are more predictable now ? maybe ?

==>

Luxmeter App versus measuring device: Are smartphones suitable for measuring illuminance?

There is an app for everything. With this promise smartphone manufacturers want to make everyday life easier for us. There are even numerous apps available for the lighting and architectural sector. Luxmeter apps. But can these replace a professional measuring device?

www.dialux.com

Luxmeter App versus measuring device: Are smartphones suitable for measuring illuminance?​

02/23/2016 Lighting technology

We are faced with this question ever more frequently because the benefit is obvious. Such apps are completely free or available at a very low price. It would really be smart to replace a luxmeter, which, depending on the manufacturer and the accuracy, costs between 100 and 2,000 Euros, with an app for the smartphone which nearly everyone has anyway.
As an accredited lighting laboratory we can only smile at the idea of anyone trying to determine a photometric parameter with a »telephone«. Yet our curiosity motivated us to get to the bottom of this matter/ to look into this matter. So we started looking for different luxmeter apps for different operating systems so that we could test them. We wanted to find out how well they compare with a calibrated class A luxmeter from our laboratory.

The hardware​

For this test we used different series of iphones as well as Sony, Samsung and Nokia devices.

Manufacturer	Operating system
iPhone5	iOS
iPhone 5S	iOS
iPhone 6	iOS
Sony Xperia Z1	Android
Sony Xperia Z2	Android
Samsung Galaxy S5	Android
Nokia Lumia 925	Windows Phone

​

The software​

We chose the following apps, most of them free, and installed them on each of the systems:

Name	Manufacturer	Operating system	Calibration option	Price
Galactica Luxmeter	Flint Soft Ltd.	iOS	no	free
LightMeter by whitegoods	Whitegoods	iOS	yes	free
LuxMeterPro Advanced	AM PowerSoftware	iOS	yes	7,99 €
Luxmeter	KHTSXR	Android	yes	free
Light Meter Pro	Mannoun.Net	Android	yes	free
Lux Light Meter	Geogreenapps	Android	yes	free
Sensor List	Ryder Donahue	Windows Phone	yes	free

​

Our reference​

We conducted the reference measurements with an Illuminance meter from PRC Krochmann (Model 106e, special model, class A). And of course with valid retraceable calibration.

The light sources used​

For this test we chose three different light sources:
-> Low voltage halogen lamp
-> Compact fluorescent lamp (correlated colour temperature: 2,700 K)
-> LED (correlated colour temperature: 3,000 K)
In order to keep everything simple and transparent we have restricted ourselves in this article to presenting the results achieved with the LED light source.

Our test setup​

The test took place in a room without daylight, unaffected by any artificial light sources. With the indicated light sources we set reference illuminances of 100 lx, 500 lx and 1,000 lx one after the other on a horizontal surface. To do this the head of the photometer of the PRC luxmeter was positioned axially below the luminaire (Gamma 0°). Then, one after the other, the different smartphones, each with their own measuring app, were used to measure the illuminance. For this the front camera, the brightness sensor on the display of the smartphone, was used. The sensor or front camera was positioned exactly at the reference point where the head of the photometer of the luxmeter had previously been positioned. This setup was maintained for all the apps with the exception of the paid app »Luxmeter Pro Advanced« since this requires the reflected light from a surface as input. The numerous settings in this app for the type of light source, the distance from the illuminated surface etc. were also adjusted. With some apps calibration is possible. This calibration was also carried out according to the manufacturer's instructions, each time with a reference calibration of 100lx.

Evaluation​

During our test we found out that, although it was possible to calibrate some of the apps to a certain value, it was frequently not possible to set this value accurately enough. So calibration was often in large increments or the reference value 100lx could not be set since the app could only be calibrated to a maximum of 34lx (iPhone 5 in combination with »LightMeter by whitegoods«). The deviations from the reference luminance were in part extremely high (up to 113% in the combination of Samsung Galaxy S 5 with the app »Lux Light Meter« from Geogreenapps). When using a reference value of 500 lx the display of the smartphone showed 1,063 lx. The lowest deviation in percent (3%) occurred with an iPhone 5 in combination with the app »LightMeter by whitegoods«. When a reference value of 500 lx was used, this smartphone displayed 484 lx. We cannot conclude however that precisely this combination will always lead to the lowest possible deviation. When a reference value of 100lx was used this app on the same smartphone was right off the mark by 89% with a displayed value of 11 lx.
The general observation is that the displayed values on the Sony devices and the Samsung and Nokia smartphones were well above the reference values, while as a rule the the iphones displayed values well below the reference values. The median deviation from the reference value measured by all the apps on the Android smartphones and on the Windows phones was on average 60% above the reference value. The median deviation of all values measured with all the different iphones was approx. 60% below the reference value.
We also noticed that the apps installed on the Samsung smartphone and on the Sony devices apparently had no influence on the value displayed. It seems that with these devices the »brightness sensor« and not the camera is used to measure illuminance. With some Samsung models it is possible to switch to the LCD test mode via the key combination *#0*#. Here, using the function »Light sensor«, you can read the alleged illuminance without installing an app. The installation of an app seems superfluous here since it apparently only serves to display a value. Nevertheless, all the values displayed by these devices also deviated by 37% to 113% from the reference value.

​

Does the same hardware in combination with the same app also lead to the same results?​

Independent of the large fluctuations in the measured values we asked ourselves whether structurally identical smartphones with the same app also display the same illuminance values. To test this we used 4 structurally identical phones of the type »iPhone 5« each with the apps »Galactica« and »LightMeter by whitegoods«. Unfortunately we suffered disappointment here, too. The diagram shows that in some cases, with the four smartphones we tested, completely different measuring results were achieved.

We suspect that the reason for these fluctuations lies in the tolerances of the components built into the phones. These are tolerances which the user does not notice in everyday use but which in direct comparisons have a great effect on the displayed illuminance values.

Is the percentage deviation from the reference value always the same?​

If you always use a smartphone with the same app, you might assume that you could still use it quite well for measuring illuminance if you already know the percentage deviation from the reference value. But is the percentage by which the value displayed by the app deviates from the reference value the same for different illuminances? To pursue this question we carried out measurements of illuminance at 10 lx, 100 lx, 1,000 lx and 10,000 lx with an iPhone 5 on the optical bench of our black laboratory. The increments can be set very accurately by adjusting the distance between the light source and the receiver. The LED luminaire with 3,000 K was used here again as a light source. In this test we looked at the values of two different apps.

As experience has shown, the values of the apps deviate from each other – in certain cases by up to 358% (12 lx to 55 lx at a reference value of 100 lx). If we look at the percentage deviations from the reference values, then no regularity of any kind is apparent.

The »Galactica« app was 180% above the reference value at 10 lx and 50% below the reference value at 10 000 lx. The »LightMeter by whitegoods« app was calibrated at 10 lx. At a reference value of 100 lx it was 88% off the mark and at a reference value of 10 000 lx 59%. All other values of the luxmeter apps were well below the reference values. There was no constant percentage deviation from the reference values. And quite incidentally we discovered that using the back camera rather than the front camera of the smartphone often produced completely different values. In addition to this, some apps never display 0 lx, not even when the camera is fitted with a lightproof cover.

Conclusion​

The results prove that serious measurement of illuminance is only possible with professional hardware. This has a V(λ)-adjusted sensor which ensures that evaluation of the incident radiation is performed according to the brightness sensitivity curve of the human eye in daylight. In addition, a cos-true evaluation is important, that means that a weighting of the incident radiation is performed according to the angle of incidence on the sensor. Smartphones can do neither the one nor the other, since otherwise their original function would not be guaranteed.
It is not the app manufacturers' intention that a smartphone should replace a professional luxmeter. The fact that some apps work with so-called calibration functions sounds professional and smart but unfortunately it is often not possible to set the value accurately. Even if it is possible, the benefit is very small since the values outside the calibrated value are subject to extreme fluctuations. Even when using the same app in structurally identical smartphones different measuring results are achieved.
Therefore apps are unfortunately not really of any great assistance for measuring illuminance and not even any use to obtain a general idea of the illuminance value. On the contrary: They lead the user in the completely wrong direction.

 

[goingrey]

In my opinion, this type of programs are worth very little.
Even if it is possible to calibrate at some point.
Comparison with a lux meter of quite good quality for class B equipment.

Calibration at a point under the light source in relation to the lux meter readings. Then try to measure on the grid. The effect is spot on and yes, it holds well. Apart from that, differences of up to 30% - the further from the light source, the worse.

I don't know to what extent this is due to a completely unknown and probably very large angular error of the smartphone camera, and to what extent it is due to, for example, very different indication errors on the phone depending on the light intensity.

I also played with one of the first versions of the photone program when you didn't have to pay anything for it.

In my opinion, this program is nothing more than an "overlay" for the lux meter that multiplies the lux result by the coefficient.

For most white LED sources, a completely reasonable but very inaccurate conversion factor is 0.015. You can even combine knowing the spectral temperature of LED and CRI or SPD in the case of practically white sources for plants and simply take measurements with a good lux meter. And then multiply the obtained values by a factor closer to the real conversion factor into photon flux in the "PAR" or ePAR range.

According to my completely private opinion, measurements taken with a smartphone with an application can be used to improve your mood or have fun. I have no idea what mistakes this could make. Maybe 10% in one case, maybe 30% in another.

This uses something used to take photos to measure brightness, and in this case it is good enough.

There's even an old comparative article somewhere: I'll give you the link in a moment - perhaps phones are more predictable now ? maybe ?

==>

Luxmeter App versus measuring device: Are smartphones suitable for measuring illuminance?

There is an app for everything. With this promise smartphone manufacturers want to make everyday life easier for us. There are even numerous apps available for the lighting and architectural sector. Luxmeter apps. But can these replace a professional measuring device?

www.dialux.com

Luxmeter App versus measuring device: Are smartphones suitable for measuring illuminance?​

02/23/2016 Lighting technology

We are faced with this question ever more frequently because the benefit is obvious. Such apps are completely free or available at a very low price. It would really be smart to replace a luxmeter, which, depending on the manufacturer and the accuracy, costs between 100 and 2,000 Euros, with an app for the smartphone which nearly everyone has anyway.
As an accredited lighting laboratory we can only smile at the idea of anyone trying to determine a photometric parameter with a »telephone«. Yet our curiosity motivated us to get to the bottom of this matter/ to look into this matter. So we started looking for different luxmeter apps for different operating systems so that we could test them. We wanted to find out how well they compare with a calibrated class A luxmeter from our laboratory.

The hardware​

For this test we used different series of iphones as well as Sony, Samsung and Nokia devices.

Manufacturer	Operating system
iPhone5	iOS
iPhone 5S	iOS
iPhone 6	iOS
Sony Xperia Z1	Android
Sony Xperia Z2	Android
Samsung Galaxy S5	Android
Nokia Lumia 925	Windows Phone

​

The software​

We chose the following apps, most of them free, and installed them on each of the systems:

Name	Manufacturer	Operating system	Calibration option	Price
Galactica Luxmeter	Flint Soft Ltd.	iOS	no	free
LightMeter by whitegoods	Whitegoods	iOS	yes	free
LuxMeterPro Advanced	AM PowerSoftware	iOS	yes	7,99 €
Luxmeter	KHTSXR	Android	yes	free
Light Meter Pro	Mannoun.Net	Android	yes	free
Lux Light Meter	Geogreenapps	Android	yes	free
Sensor List	Ryder Donahue	Windows Phone	yes	free

​

Our reference​

We conducted the reference measurements with an Illuminance meter from PRC Krochmann (Model 106e, special model, class A). And of course with valid retraceable calibration.

The light sources used​

For this test we chose three different light sources:
-> Low voltage halogen lamp
-> Compact fluorescent lamp (correlated colour temperature: 2,700 K)
-> LED (correlated colour temperature: 3,000 K)
In order to keep everything simple and transparent we have restricted ourselves in this article to presenting the results achieved with the LED light source.

Our test setup​

The test took place in a room without daylight, unaffected by any artificial light sources. With the indicated light sources we set reference illuminances of 100 lx, 500 lx and 1,000 lx one after the other on a horizontal surface. To do this the head of the photometer of the PRC luxmeter was positioned axially below the luminaire (Gamma 0°). Then, one after the other, the different smartphones, each with their own measuring app, were used to measure the illuminance. For this the front camera, the brightness sensor on the display of the smartphone, was used. The sensor or front camera was positioned exactly at the reference point where the head of the photometer of the luxmeter had previously been positioned. This setup was maintained for all the apps with the exception of the paid app »Luxmeter Pro Advanced« since this requires the reflected light from a surface as input. The numerous settings in this app for the type of light source, the distance from the illuminated surface etc. were also adjusted. With some apps calibration is possible. This calibration was also carried out according to the manufacturer's instructions, each time with a reference calibration of 100lx.

Evaluation​

During our test we found out that, although it was possible to calibrate some of the apps to a certain value, it was frequently not possible to set this value accurately enough. So calibration was often in large increments or the reference value 100lx could not be set since the app could only be calibrated to a maximum of 34lx (iPhone 5 in combination with »LightMeter by whitegoods«). The deviations from the reference luminance were in part extremely high (up to 113% in the combination of Samsung Galaxy S 5 with the app »Lux Light Meter« from Geogreenapps). When using a reference value of 500 lx the display of the smartphone showed 1,063 lx. The lowest deviation in percent (3%) occurred with an iPhone 5 in combination with the app »LightMeter by whitegoods«. When a reference value of 500 lx was used, this smartphone displayed 484 lx. We cannot conclude however that precisely this combination will always lead to the lowest possible deviation. When a reference value of 100lx was used this app on the same smartphone was right off the mark by 89% with a displayed value of 11 lx.
The general observation is that the displayed values on the Sony devices and the Samsung and Nokia smartphones were well above the reference values, while as a rule the the iphones displayed values well below the reference values. The median deviation from the reference value measured by all the apps on the Android smartphones and on the Windows phones was on average 60% above the reference value. The median deviation of all values measured with all the different iphones was approx. 60% below the reference value.
We also noticed that the apps installed on the Samsung smartphone and on the Sony devices apparently had no influence on the value displayed. It seems that with these devices the »brightness sensor« and not the camera is used to measure illuminance. With some Samsung models it is possible to switch to the LCD test mode via the key combination *#0*#. Here, using the function »Light sensor«, you can read the alleged illuminance without installing an app. The installation of an app seems superfluous here since it apparently only serves to display a value. Nevertheless, all the values displayed by these devices also deviated by 37% to 113% from the reference value.

​

Does the same hardware in combination with the same app also lead to the same results?​

Independent of the large fluctuations in the measured values we asked ourselves whether structurally identical smartphones with the same app also display the same illuminance values. To test this we used 4 structurally identical phones of the type »iPhone 5« each with the apps »Galactica« and »LightMeter by whitegoods«. Unfortunately we suffered disappointment here, too. The diagram shows that in some cases, with the four smartphones we tested, completely different measuring results were achieved.

We suspect that the reason for these fluctuations lies in the tolerances of the components built into the phones. These are tolerances which the user does not notice in everyday use but which in direct comparisons have a great effect on the displayed illuminance values.

Is the percentage deviation from the reference value always the same?​

If you always use a smartphone with the same app, you might assume that you could still use it quite well for measuring illuminance if you already know the percentage deviation from the reference value. But is the percentage by which the value displayed by the app deviates from the reference value the same for different illuminances? To pursue this question we carried out measurements of illuminance at 10 lx, 100 lx, 1,000 lx and 10,000 lx with an iPhone 5 on the optical bench of our black laboratory. The increments can be set very accurately by adjusting the distance between the light source and the receiver. The LED luminaire with 3,000 K was used here again as a light source. In this test we looked at the values of two different apps.

As experience has shown, the values of the apps deviate from each other – in certain cases by up to 358% (12 lx to 55 lx at a reference value of 100 lx). If we look at the percentage deviations from the reference values, then no regularity of any kind is apparent.

The »Galactica« app was 180% above the reference value at 10 lx and 50% below the reference value at 10 000 lx. The »LightMeter by whitegoods« app was calibrated at 10 lx. At a reference value of 100 lx it was 88% off the mark and at a reference value of 10 000 lx 59%. All other values of the luxmeter apps were well below the reference values. There was no constant percentage deviation from the reference values. And quite incidentally we discovered that using the back camera rather than the front camera of the smartphone often produced completely different values. In addition to this, some apps never display 0 lx, not even when the camera is fitted with a lightproof cover.

Conclusion​

The results prove that serious measurement of illuminance is only possible with professional hardware. This has a V(λ)-adjusted sensor which ensures that evaluation of the incident radiation is performed according to the brightness sensitivity curve of the human eye in daylight. In addition, a cos-true evaluation is important, that means that a weighting of the incident radiation is performed according to the angle of incidence on the sensor. Smartphones can do neither the one nor the other, since otherwise their original function would not be guaranteed.
It is not the app manufacturers' intention that a smartphone should replace a professional luxmeter. The fact that some apps work with so-called calibration functions sounds professional and smart but unfortunately it is often not possible to set the value accurately. Even if it is possible, the benefit is very small since the values outside the calibrated value are subject to extreme fluctuations. Even when using the same app in structurally identical smartphones different measuring results are achieved.
Therefore apps are unfortunately not really of any great assistance for measuring illuminance and not even any use to obtain a general idea of the illuminance value. On the contrary: They lead the user in the completely wrong direction.

That's disheartening.

 

[NIKT]

Why ? The smartphone is not a measuring device. This is the toy that everyone is now addicted to.

=> TES 1335

this one also seems to be useful. based on comparison with better quality equipment. also far from ideal. These good and reliable A grades cost completely different money. They may not be particularly pretty, but they display reasonable numbers as results

 

[Hiddenjems]

The iPhone version uses a diffuser over the camera to fix the angle problem, and the intensity cap.

I don’t represent the company, I just have a $15 app that works reasonably well compared to quantum meters.

 

[NIKT]

I don't have an iPhone. I have an Oppo . I also tried camera overlays. from a piece of paper to a translucent plastic sphere similar to those on b clas light meters sensors. It was a short-term fun and I still think that even compared to a good class B lux meter, it's just a toy for a child.

It may be better than what happened in 2016, but I still don't take it seriously.

The comparison of the sound measurement application with a professional meter was the same. Class A

ps: a class A lux meter will probably be more expensive than an iPhone. edit -> I checked about x2

 

[Hiddenjems]

I don't have an iPhone. I have an Oppo . I also tried camera overlays. from a piece of paper to a translucent plastic sphere similar to those on b clas light meters sensors. It was a short-term fun and I still think that even compared to a good class B lux meter, it's just a toy for a child.

It may be better than what happened in 2016, but I still don't take it seriously.

The comparison of the sound measurement application with a professional meter was the same. Class A

ps: a class A lux meter will probably be more expensive than an iPhone. edit -> I checked about x2

I don’t think anything, I’ve used my iPhone app in the same room as a quantum meter, and the differences are negligible. These are high ceiling rooms with 25-30 1000w de’s so the light is spread out better.

 

[NIKT]

can show data and photos.
Measuring on a grid. ?
Curiosity

youtube :





etc.

I did a similar comparison, but without a PAR meter. And with the phone I have.
Class B Tes luxmeter which, compared to class A, was 3.5% behind the average when measured on a grid. (in a given measurement situation, it was not possible to compare it to a greater extent.)

The results I obtained were more or less like this - completely unpredictable deviations. not only under artificial light sources but also when playing with variable natural lighting in the room and outside.

Hence my opinion is this and not different. If I didn't have something to compare what the apps showed me, I probably wouldn't have any opinion of my own.

Am I right in considering applications and phones as toys and not something that is actually suitable for measurements? Isn't it hmm... It's not for me to judge. Everyone believes what they want. Nowadays, measurements using smartphones are fashionable. It basically costs nothing.

ps: a cheap Chinese lux meter, one of the simplest ones, compared to a relatively predictable lux meter, it was similarly bad, very similar. Also not very predictable drift - but there was no possibility of point calibration.


in a completely off-topic mode. Measurements can be made with anything that responds to light. If

1. the response is proportional to the intensity, preferably linear. and is known.
2. the angular error of the measuring head is small.

It can even be an ordinary silicon photodiode with a sensible cover that will eliminate the impact of the response related to the angle of the incident light.

This can be connected to a regular precision voltage meter.

The condition for this to work is the calibration of the response for a given light source - known SPD. in this case, calibration is understood as a known conversion factor.

And in my opinion, even if phones now have much better "cameras" and the difference between parameters, not only between different models and brands, and even between supposedly identical phones of the same brand, is not as huge as shown in that old article, there is a problem with playing in measurements including.

If you do not have a reference against which you can calibrate something and you only use constants embedded in the program, such as:

sun, warm LED, grow LED, etc. The error may reach 10 or more%.

This will result errors from the lack of calibration of the phone itself against anything at the very start. And unknown spread of parameters between phones itself even the same brand.

According to some videos on the tube and according to the general opinion (very common), it is good, everyone uses it and is satisfied.
However, as a born Doubting Thomas, I will be on the side of the minority report. it seems to me that in this case it is better to have a predictable lux meter in your hand and a relatively accurate conversion factor calculated for the SPD data of a specific source rather than a smartphone. Private opinion

 

[Kathryn Kelly]

Pocket Light Meter.
myLightMeter Pro.
Lumu Light Meter.
Lux Meter.
Light Meter.
The above applications are all top selected applications or you can refer to Modilimitado APK Mod for more information

 

[Ca++]

PAR meters are getting cheaper. A box that bluetooths to your phone, is just $80US in Amazon, with full sized meters $150 there. While Ali will sell you one for 100.

I would be happy enough with the 6% error of the s22 running photone, when compared with the $600 apogee. A meter that itself says a 5% error can be expected.
Right now, I'm happy enough with the $10 light meter that converts to ppf easily (without needing a calc)
10% wouldn't bother me that much. Who am I comparing with? I just need repeatable results. Over the net I might compare, but then you really need to apply 10% error to anything you hear anyway. They might be using an iphone or something crazy like that.

 

[hillbil]

Photone App is extremely helpful, even the free version. The $4/month version absolutely nails the color temperature of any source I tried.

 

[goingrey]

I have been using the Photone app. It does seem to show a bigger number with more light and a smaller number with less. So it's not totally useless even if the values aren't "real", you can use it to see which areas have a similar amount of light. Then again, the back of your hand, also gives an indication. If it looks the same then the amount of light is similar.

 

[hillbil]

Photone tested within about 5% of the Appogee with an old IPhone 7 like mine. I have found it very useful in a practical sense.

 

[Ca++]

My lux meter is $5 for new ali customers, or about $10 for existing one's. It's not $4 every month. For $5 you own it. Actual hardware. I think $50 a year is just too much for an app. $80 gets a real par meter, that goes in the usb port. No converting lux meter readings to flaky par numbers. An actual par sensor.
I really wouldn't want an app doing my math for $50 a year. Which is all it is. The phone has no par meter hidden away. Just a light sensor, it doesn't hide at all (though maybe an iphone does)
I dial *#01*# on my sammy, then select sensors, light sensor. I get lux, r g b w cct.
I cba though. My $10 meter is just beside my drivers, and only needs the power button pressing.
If you are a numpty, don't use the engineer code. You may re-calibrate stuff you don't want to. Just pay for an app.