- a modestly designed digital light meter capable of measuring the current level of illumination in a room using the built-in sensors of a smartphone or tablet on an android platform: the main features of such a technical tool are intuitive control, excellent optimization, and a minimum of settings. Before the very first measurements, the developers from My Mobile Tools Dev strongly recommend that you look into the calibration section and go through several tests that allow you to bring the accuracy when "finding suites" to the maximum.

The preparatory procedures will take a minimum of time, but the result will really surprise (according to users, without the starting setting, the measurement accuracy is close to zero, but it is worth completing several tests and a real lux meter can be safely replaced with a digital copy -)! But first things first:
1. Interface. A black static background, a gray font blending in with the decorations, just a few buttons allowing you to either look into the settings section or start new measurements.

From the interesting - the ability to save statistics and make a kind of "sample" for the day, week or month - for example, the average value of the suites in the room, maximum or minimum. Information, of course, purely for the sake of "interest", nothing more. But for the opportunity to measure everything around the developers, we should also thank - the sensations are unforgettable.
2. Graphs. All the plates, menus and graphs displayed in the center of the screen look much more interesting. Here, for example, is the current state of illumination, there - for the recent hour, and even further - for the last day.

There are many strips, everything can be viewed and studied.
Of the minuses - advertising is sometimes very annoying, sometimes the system shows strange results, sometimes it is impossible to measure at all.

Otherwise, a free lux meter for android can help a lot - be sure to try and share with your friends!

LED lighting has become a part of our lives, LED bulbs are already sold even in grocery stores, and there are even more LED bulbs on the shelves of household and construction supermarkets than conventional incandescent and compact fluorescent (energy-saving) bulbs combined.

Unfortunately, manufacturers often deceive customers by indicating on the packaging very high values ​​of the luminous flux and the equivalent of an incandescent lamp. You buy a lamp that says "600 lumens, 60W incandescent equivalent", bring it home, turn it on and realize that it is clearly dimmer than a 60W incandescent lamp. Fortunately, under consumer rights law, LED bulbs can be returned to any store within 14 days (and to many hypermarkets within 30, 60 days, or even a year). Refunds are possible due to the fact that light bulbs (including LED ones) are still not considered a complex technical product.

In order to understand how much light the lamp actually gives, you need to measure its luminous flux. Usually, expensive laboratory equipment (goniophotometers, measuring integrating spheres) is used to measure the luminous flux (the total amount of light that a lamp gives), which costs tens of thousands of dollars. I propose a method that allows you to accurately measure the luminous flux of the lamp, spending only 87 rubles.

The main problem when measuring the luminous flux is the unevenness of light brightness in different directions for different types of lamps. Some lamps shine more forward, some shine more to the sides, some shine almost evenly in all directions.

To measure, you need to somehow get the average value of the brightness of the lamp. Typically this is done by placing the lamp inside an integrating sphere coated with an ultra-white matte barium sulfate paint. The light reflects off the walls many times and hits the sensor. The goniophotometer rotates the lamp horizontally, takes multiple brightness measurements at each pivot point, and calculates the total amount of light that the lamp gives. We'll do it easier.

We need a lamp with a spherical matte plastic cap. This matte cap will average the brightness of the lamp in different directions. Such a lamp can be bought for 87 rubles in Leroy Merlin stores. In the picture there is another lamp with a glass shade - do not pay attention: the stores themselves have what you need.

The exact name of the lamp is "Lamp NBB-60 (straight base), plastic ball, white", manufactured by Axioma LLC, Moscow.

Almost any Android smartphone can be used as a brightness meter (lux meter). Most smartphones have a light sensor (located above the screen) that is used to adjust the brightness of the screen based on ambient light.

There are many luxmeter programs in the Play Market, I recommend installing the simple and convenient Sensors Multitool program. After starting the program, go to the Light tab and see the illumination value. The light meter for all smartphones is not calibrated, and for different smartphones it will show completely different values, which may differ from the real ones by half, but this will not affect the accuracy of our measurements.

We fix the lamp to any surface (I used a piece of plywood). We attach the smartphone to a carton of milk or juice with two rubber bands.

For the measurement, we need a reference lamp. I recommend using an IKEA 600 Lm 303.059.76 LED1466G9 lamp. This lamp has a luminous flux that exactly matches the declared one, and a very small variation in luminous flux from different copies.

Of course, you can use an ordinary incandescent lamp, but it is important to remember that, firstly, the luminous flux of incandescent lamps depends very much on the voltage in the network, and secondly, different copies of lamps produced by Russian and Belarusian factories can vary greatly in luminous flux. Nevertheless, you can always find out whether an LED lamp gives more or less light compared to an incandescent lamp.

We twist the shade, turn on the lamp, place the fixed smartphone in front of the lamp, start the program. We calibrate our measurement system: we shift the bag with the fixed smartphone so that the smartphone's luxmeter shows exactly 600 lux (if we have a 600 lumen lamp as a standard). Now we unscrew the reference lamp and screw in the lamp that we want to test without changing the distance between the lamp and the smartphone. The smartphone will display a value that will correspond to the luminous flux of the measured lamp.

I tested this simplest measuring setup on seven lamps with a luminous flux from 200 to 1000 lumens and two smartphones - Sony Z3 Dual and ZUK Z1. The measurement accuracy was 1-15%.

LED lamps have one feature - as they warm up, their luminous flux decreases by 11-12% within half an hour. We measured the lamps immediately after switching on, but since the reference lamp was also cold, our entire measuring system was more or less accurate.

You can increase the measurement accuracy if you use any luxmeter instead of a smartphone. Even the cheapest Chinese will do, for $ 10. It may be poorly calibrated, but again, this will not affect the accuracy of our measurements. It is better to warm up the reference lamp and those lamps whose luminous flux we want to measure for half an hour. The light meter must also be rigidly fixed and positioned at such a distance from the luminaire so that it shows exactly as many lux as the number of lumens given by the reference lamp.

I measured the luminous flux of the same seven lamps with the Lupine light-pulse meter.

The measurement accuracy has become significantly higher - the error is only 0-3%.

Note that all official accredited laboratories also have measurement discrepancies. The picture below shows the results of measuring the luminous flux of the same lamp in 54 different laboratories. The average discrepancy was 3%, maximum 26%.

So, on my knees, I managed to achieve the measurement accuracy that not all laboratories can boast of.

For people who constantly work in the office, good illumination of the workplace is important. If there is little light, fatigue increases and the quality of vision may decrease. The Luxmeter program will help to check the illumination on the desktop, which can be installed on any Android smartphone.

What kind of illumination is considered sufficient

According to Russian SNiP standards, the illumination of a desktop in an office should be approximately 300 Lx. But doctors advise more value. In this regard, the European standards, requiring at least 1000 Lx, agree with them. If you care about your health, use a figure between 300 and 1000 Lx as a guide.

Install a table lamp to increase the amount of light. Or use more powerful light bulbs in your ceiling lights.

How to measure illumination with a smartphone

Install the Luxmeter program from the official Google Pay app store. Immediately after the first start-up, the display shows the light intensity expressed in lux.

In the upper left corner, for comparison, a pictogram of a light source giving such a luminous flux is shown. In the picture above, 953 Lx corresponds to the sun on a cloudy day. When moving away / approaching the phone to the light source, the value changes, a graph is shown on the display.

According to user reviews, the application works at the level of professional devices. The readings at 1000 Lx differed by about 50 Lx, which gives a measurement accuracy of 5%. At home, this error can be neglected.

The setting provides a calibration mode. By default, the value is supplied from the phone sensor. However, you can set a factor to increase or decrease the value.

Description

9Apps will deliver free android apps. 30,000+ users downloaded Lux ​​Meter latest version on 9Apps for free every week! Fortunately, this popular app is easy to get. And it was hot and it was released on 2016-02-23. For more information, you can visit our official website - 9Apps.
deluxe meter is a new Android based mobile application provided free of charge in the play store as a very useful tool. This app, when installed, can be used extensively to measure illumination like FC and Lux. this is done using the app via light sensors in Mobile. This app uses the best of mobile and allows you to measure in Lux or FC and linked. This Android phone based luxury meter app is only intended to provide visual comfort to the user. measuring light and its efficiency through a brief analysis in daylight, just an android application is that funny. While various other apps exist, the suite meter steals the show with amazing uses. If you are a company owner, this application would be the perfect choice. Just download the Lux Meter Android Application and check the ideal light meter possible in your work space. This app is ideally guided in the best way to drive you to a better workplace environment for your employees. it helps in displaying preference for the calibration factor, accurate and would be an ideal choice for any user. How to use the app: Given the use of this app, the way to use the suite meter is pretty simple as well. all you need to do is connect to the play store right away and download with a quick search for it. This application has a simple look, promising to make the best use of it. choose a place where you would like to check the illumination. just select the one you would like to check, this app also supports min and max values ​​as well. The yellow background of the application represents the luminance itself, this value is given in bold, and then the maximum luminance value is the minimum value, and also, one is saved for quick access. This luxury meter will give you accurate values ​​of all the above instantly. use the Checking counter, which gives before and after along with the multiplier value. adjust light sources and get value instantly. reset the value as needed. Features and Benefits: This application is completely free, just connect to the play store and start downloading. it's bug free. It has built-in multiplier correction. supports suite widely. supports the legs of the candle. The user interface is very friendly. consumes less memory, it requires Android 2.1+. the measure differs depending on the device. use it across the spectrum. A good range promises enough. Convenient navigation. testing on bike and car lights is easy. value records easily. do not consume more data. There are countless unnecessary applications in our mobile, this application will not fall under their list. Fitting and getting great benefit from it.illuminance is key these days to make the best use of it and shine. measure where and when required, stay enlightened with backlit measures for life.

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This article is an translation articles Luxmeter App versus measuring device:
Are smartphones suitable for measuring illuminance?

For smartphones, there are many applications that make our lives easier. There are numerous applications for lighting technicians. But does this mean that you can use a smartphone to measure illumination?

We are asking this question more and more often because the benefits are clear. After all, such applications are free or not very expensive. It would be great to replace the light meter, which, depending on the manufacturer and the accuracy, costs between 100 and 2000 euros. (aliexpress does not agree and shows amounts even less than 10 euros), to an application for a smartphone, which almost everyone already has.

As an accredited lighting laboratory, we can only smile at the idea of ​​measuring illumination with a smartphone. Nevertheless, we found this idea very interesting, which prompted us to conduct an experiment. So we started looking for different applications for different operating systems. We wanted to find out how accurately they measure compared to the lux meter from our laboratory.

Hardware

For this test, we used various iPhone models as well as Sony, Samsung and Nokia.

Software
We have installed the following applications, most of which are free:

Reference instrument

We carried out control measurements with a luxmeterPRC Krochmann (Model 106e, special model, class A)And, of course, the instrument was calibrated.

Light sources used

For this test, we selected three different light sources:

· low voltage halogen lamp

· compact fluorescent lamp (color temperature: 2700 K)

· LED (color temperature: 3000K)

In order not to complicate the article, we left only LED source.

Our test setup

The test was carried out in a dark room without artificial and natural light sources. For the light sources used, we set the illumination alternately at 100 lux, 500 lux and 1000 lux (probably still 2000) on a horizontal surface. For this, the photometric head of the luxmeter was positioned perpendicular to the luminaire axis.

Then, smartphones with various applications were also obstructed, so that the front camera and the brightness sensor were under the lamp. The sensor or front camera was located exactly at the point where the photometric head of the luxmeter was previously located.

This is how all devices were located, except for iPhone with the paid app "Luxmeter Pro Advanced" as this app for measuring illumination involves measuring the light reflected from a surface. There are a lot of settings in this application including types of light sources, distance to light source, etc.

Also, when using some applications, calibration is possible. Calibration was carried out in accordance with the instructions, namely 100LK.

Grade

During our test, we found that although calibration in some applications was possible to a certain value, it was not possible to set the value accurately enough. This happened due to the fact that the step with which the value was set was large, or the value of 100 lux was not set at all, for example, in the application LightMeter by whitegoods for iPhone 5, the calibration value was set to a maximum of 34 lux.

The deviations from the reference values ​​were sometimes quite high (reaching 113% for the Samsung Galaxy S5 with the Geogreenapps 'Lux Light Meter' app). When the reference value was set to 500 lux, the smartphone display showed a value of 1.063 lux. The lowest percentage deviation (3%) was recorded using the iPhone 5 and the app “ LightMeter by whitegoods " ... When the reference value was set to 500 lux, this smartphone showed 484 lux. However, we cannot conclude from this that this particular smartphone with a specific program will always show the correct value. When the illumination was set to 100 lux and when the same application was used on the same smartphone, the deviation reached 89% and the device showed 11 lux.

We were able to identify a trend that the displayed values ​​on devices from Sony, Samsung and Nokia were significantly higher than the reference values, while, as a rule, on iP hone, the displayed values ​​are well below the reference values. Average deviation from the reference value measured in all applications on Android smartphones and Windows phones Phone were, on average, 60% higher than the reference values.

Average deviation of all values ​​measured by different iPhone was 60% below the reference values. We also noticed that various apps installed on smartphones from Samsung and Sony showed similar values. Apparently, these models use a brightness sensor for measurement, not a camera.

In some Samsung models, you can switch to the engineering menu mode - by typing the combination * # 0 * # from the keyboard. By selecting the "Light Sensor" menu item, you can find out the estimated illumination without installing the application. So the installation of applications in this case will be superfluous. However, all values ​​displayed by these devices also deviated from 37% to 113% of the reference value. Galactica Luxmeter "and" LightMeter by whitegoods ". Unfortunately, here too we were disappointed. The diagram shows that the four smartphones we tested showed completely different measurement results in some cases.

We suspect that the reason for these fluctuations is the use of components that are different from each other, which the user does not notice in day-to-day use, but becomes noticeable when compared directly.

Is the dynamics of percentage deviations from the reference value maintained?

If you always use a smartphone with the same application, you can assume that measurements can be made fairly accurately if you already know the percentage deviation from the reference value.

But is it always the same percentage by which the value deviates? To answer this question, we measured illumination at 10 lux, 100 lux, 1000 lux and 10,000 lux using an iPhone 5 located on an optical bench in our black room. The brightness gain can be very precisely set by adjusting the distance between the light source and the receiver. The light source was again an LED light source with a color temperature of 3000 K.

In this test, we looked at the readings of two different applications. Experience shows that application values ​​deviate from each other - in some cases up to 358% (values ​​range from 12 lux to 55 lux with a reference value of 100 lux), if we look at the percentage of deviations from the reference values, we will not see any pattern ...

When using the application " Galactica Luxmeter ”values ​​were higher180% reference at 10 lux and 50% below reference at 10,000 lux.

When using the application " LightMeter by whitegoods »Calibrated to 10 lux. At a reference value of 100, the deviation was 88% downward, and at 10,000 lux, 59%. The values ​​of all the others attached were also significantly lower. For all other values, the readings were also lower.

Quite by accident, we found that measurements taken with the front and rear cameras show different values. In addition to this, some applications never show 0 lux, even if the camera is not exposed to any light and is covered with a blank.

Conclusion

The results prove that serious illumination measurements are only possible with professional equipment. It is equipped with a calibrated sensor to ensure that the illumination assessment is carried out in accordance with the sensitivity of the human eye.

In addition, the devices allow assessing the illumination depending on the angle of incidence of the beam. Smartphones cannot do either one or the other, as otherwise they will not be able to perform their functions.

Despite the fact that the developers claim that they can replace professional instruments, since there are various smart functions such as calibration in their applications, calibration does not allow setting accurate values. And even if it is possible, it will still cause deviations in the measurements. Even when using the same app and identical smartphones, different measurement results are obtained.

Therefore, unfortunately, applications are actually useless - even just to get a general idea of ​​the illumination.

from Thomas Pittner and Jaqueline Goldschmidtabout