- 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 the Android platform: the main features of such a technical instrument are intuitive control, excellent optimization, and a minimum of settings. Before the first measurements, the developers from My Mobile Tools Dev strongly recommend that you look into the calibration section and pass several tests that allow you to bring the accuracy of the "search for lux" to the maximum.

The preparatory procedures will take a minimum of time, but the result will really surprise you (according to users, without a start-up setting, the measurement accuracy is close to zero, but once you finish a few tests, you can safely replace a real light meter with a digital copy -)! But first things first:
1. Interface. A black static background, a gray font that blends in with the scenery, just a few buttons that allow you to either look into the settings section or start new measurements.

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

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

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

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

There are many applications for smartphones that make our lives easier. There are many applications for lighting technicians. But does this mean that you can use your smartphone to measure light?

We ask this question more and more often, because the benefits are obvious. 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 accuracy, costs between 100 and 2000 euros (aliexpress does not agree and shows amounts even less than 10 euros), to the smartphone app that almost everyone already has.

As an accredited lighting laboratory, we can only smile at the idea of ​​measuring light with a smartphone. Nevertheless, this idea seemed to us very curious, which prompted us to conduct an experiment. So we started looking for different apps for different operating systems. We wanted to find out how accurate they are compared to the light meter in our lab.

Hardware

For this test, we used various models iPhone, 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 using a light meterPRC Krochmann (Model 106e, special model, class A)And, of course, the device was calibrated.

Used light sources

For this test, we chose three different source Sveta:

· low voltage halogen lamp

· compact Fluorescent Lamp(color temperature: 2700K)

· LED (color temperature: 3000K)

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

Our test setup

The test took place in a dark room without sources of artificial and natural light. For the light sources used, we set the illumination alternately to 100 lux, 500 lux and 1000 lux (probably still 2000) on a horizontal surface. To do this, the photometric head of the luxmeter was located perpendicular to the lamp axis.

Then, smartphones with various applications also went crazy 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 light meter was previously located.

All devices were arranged in this way, with the exception of iPhone With paid application"Luxmeter Pro Advanced" because this illuminance measurement application measures the light reflected from a surface. There are quite a lot of settings in this application, including the types of light sources, the distance to the 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 it was possible to calibrate to a certain value in some applications, 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 100lx was not set at all, for example, in the application LightMeter by whitegoods for iPhone 5, the value for calibration was set to a maximum of 34lux.

Deviations from the reference values ​​were sometimes quite high (up to 113% for the Samsung Galaxy S5 with the "Lux Light Meter" application from Geogreenapps). When the reference value was set to 500 lux, the display of the smartphone displayed a value of 1.063 lux. The lowest percentage deviation (3%) was recorded when using the iPhone 5 and the application " LightMeter by whitegoods» . When setting the reference value 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 using the same application 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 benchmark measured across all apps on Android smartphones and Windows phones Phone were on average 60% higher than the reference values.

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

In some Samsung models you can switch to mode engineering menu- by dialing the *#0*# combination from the keyboard. By selecting the "Light sensor" menu item, you can find out the estimated illumination without installing the application. So installing 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 chart 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 everyday use, but becomes noticeable in direct comparison.

Does the trend in percentage deviations from the reference value persist?

If you always use a smartphone with the same app, you can assume that you can measure accurately enough 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 with an iPhone 5 placed on an optical bench in our black room. The brightness increment can be very precisely set by adjusting the distance between the light source and the receiver. An LED light source with a color temperature of 3000 K was again used as the light source.

In this test, we looked at readings from 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 value of deviations from reference values, then we will not see any pattern .

When using the application " Galactica Luxmeter" values ​​were higher180% of 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% down, and at 10,000 lux, 59%. The values ​​of all other applied ones were also significantly lower. For all other values, the readings were also lower.

Quite by chance, we found that the 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 it is closed with a "plug".

Conclusion

The results prove that serious light measurements are only possible with professional equipment. It is equipped with a calibrated sensor, which ensures that the illuminance evaluation will be carried out in accordance with the sensitivity of the human eye.

In addition, the devices make it possible to evaluate the illumination depending on the angle of incidence of the beam. Smartphones can't do either, otherwise they won't be able to perform their functions.

Although the developers claim that they can replace professional instruments, since their applications have various smart functions such as calibration, but calibration does not allow you to set accurate values. And even if this is possible, then there are still deviations in the measurements. Even when using the same application and identical smartphones, you get different results measurements.

Therefore, unfortunately, applications are really useless - even just to get a general idea of ​​\u200b\u200blight.

from Thomas Pittner and Jaqueline Goldschmidtabout

IN App Store there are applications that are very simple, even primitive, which at some point may turn out to be very useful. In this collection - a light meter, sound level meter and a counter of everything in the world right from Artemy Lebedev himself.

Luxmeter

With this application, you can measure the illumination of a certain place (for example, a room or a desktop) and compare the results with standards. If there is not enough light, it's time to change the light bulb to a more powerful one so as not to constantly spoil your eyes during work.

The main screen of the application - three menu items: "Illumination Standards", "Measurements" And "Story". In the first section, the illumination is measured and compared with standard values. If everything is good and there is enough light, corresponding marks appear in the lines of standards.

Measurements are made by three methods: constantly, once and by timer. The first two options do not need to be explained, but the measurement by timer means only a delay in the start of the measurement of 10 seconds. It must be possible to have time to turn on all the light bulbs.

On the screen "Measurements" there is no comparison with standard values, but there is an image measuring device, the same luxmeter. The measurement options are the same as in the previous screen. You can set a marker on the scale of the device, marking, for example, the result of the previous measurement (before replacing the light bulb with a new one) - a convenient feature.

On the screen "Story", as you might guess, the measurement history is available. To save the results during the measurement, you just need to click the "Save" button in the upper right corner of the screen. There is nothing special in the "History" - only background information.

Of course, Luxmeter is not a professional measuring tool. But in everyday life, most often, special measurement accuracy is not needed. The application also allows you to conclude whether the current lighting is harmful to the eyes, whether it is time to strengthen it. In the end, the benefits are undeniable.

Product Information

Developer: Application Manufactory.

Cost: free.

Requirements: compatible with iPhone, iPod touch(4th generation), iPad 2 Wi-Fi, iPad 2 Wi-Fi + 3G, iPad (3rd generation) and iPad Wi-Fi + 4G. Requires iOS 4.0 or later.

Decibels

About it free app not much to say. It's just a virtual instrument on the iPhone screen showing the current noise in decibels. That's all. None additional features, no settings, no frills in interface design. Just a scoreboard, automatic measurement and - the result.

Lebedev Studio counter

Studio designers tried to turn the most banal tool for counting into a convenient and beautiful application. And, I must say, they succeeded. The case when the application is both convenient to use and pleasant to look at.

Is it worth it to buy expensive equipment for measuring illumination, if smartphone manufacturers have developed special programs allowing you to take measurements with a regular smartphone?

Let's look into this topic.
On the website of one of the smartphone manufacturers they write: "In order not to be in a difficult situation, usually this problem solve with the help of a special device - a light meter, but today it is better to replace expensive inventory with the iPhone application of the same name, which can be downloaded from the App Store ... "
"The Luxmeter application uses data obtained from the front or rear camera of a smartphone to determine the degree of illumination, and is a real pocket light meter. The program is calibrated using the ATT-1508 light meter: the calibration sample is 5000 measurements, and the coefficient of determination is 0.87 (with future updates - 0.9 over the entire measurement range) - all this guarantees exceptional measurement accuracy.
Or we read "The Luxmeter application was created so that its users can save on the purchase of expensive professional equipment"!!!
Do you believe this? I doubted for a very long time. Maybe they write it right. I downloaded a program for myself and measured the illumination. I got 53 suites on my desktop and decided that not everything is going smoothly here. But I decided that I should try and compare with a good light meter, but my hands never reached the experiment.
And finally, DIAL, the lighting professional who developed the DIALux and DIALux evo software, which also has its own laboratory and conducts measurements and scientific activities, got down to business and tested smartphones and applications for measuring lighting.
The experiment involved:

For the experiment, lighting levels were measured from 3 types of light sources: low-voltage halogen lamp, compact Powersave lamp(2700K) and LED lamp (3000K).
For ease of understanding, see the results for LED in the graph. That is, the measurements were carried out for all lamps, but the results were published only for the light source: LED.

Measurements were taken for all smartphones. To do this, in a special laboratory, illumination levels of 100 lux, 500 and 2000 lux from the tested light source were planned.
The results are surprising. In only one case, when measuring 500 lux, the iPhone5 showed a result of 484 lux, which is a very close value. In all other cases, the measurements were in the range from 37 to 113%.
After such results, DIAL decided to check several identical iPhone smartphones 5 and applications "Galactica" and "LightMeter by whitegoods".

Unfortunately, there was no unity of results here either.
DIAL experts conclude that, unfortunately, it is not necessary to measure light levels using smartphones in non-professional, non-home conditions. Based on experiments with various smartphones and various software it was found that such measurements have neither accuracy nor correctness. Everything depends on the case.

Based on the article: "Luxmeter-App vs. Messgerät: Sind Smartphones zum Messen geeignet?" by Jaqueline Goldschmidt and Thomas Pittner
Photos from DIAL.de

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

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, European standards agree with them, requiring at least 1000 Lx. If you care about your health, then use a figure between 300 and 1000 Lx as a guideline.

To increase the amount of light, set table lamp. Or use more powerful light bulbs in ceiling lights.

How to measure illumination with a smartphone

Install the Luxmeter program from the official store Google Apps pay. Immediately after the first switch on, the display shows the light intensity expressed in lux.

In the upper left corner, for comparison, an icon of a light source is shown that gives such a luminous flux. In the picture above, 953 lx corresponds to the sun on an overcast day. When the phone moves away/closer to the light source, the value changes, the 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 an accuracy of measurements at the level of 5%. At home, such an error can be neglected.

The setting provides a calibration mode. By default, the value is taken from the phone sensor. But you can set a factor that increases or decreases the value.