Exposure Light Lux Meter

Easily measure light intensity in any environment with either the light sensor (incident measurement) or the back or front camera (reflective measurement / spot metering).

The app also has an easy to use full-time manual override exposure meter to quickly find the optimal exposure settings for your camera.

What is Illumination?
Illuminance is a measure of light intensity, indicating "how strong the light is". Specifically, it quantifies the amount of light falling on a surface per unit area. This metric gauges the effectiveness of surface illumination and is commonly expressed in lux (lumens/m2), foot-candles (fc), or exposure value (EV). The app supports all three units, allowing you to seamlessly switch between them by simply clicking on the circular unit button located in the top-left corner of the Home tab.

How to Use the Exposure Picker?
The app has a built in Exposure Picker, also known as an Exposure Meter. It is a powerful tool designed to help you determine optimal exposure settings for your camera. Here is how you can make the most of it:
You have the flexibility to adjust the Aperture (f-stop setting), Speed (shutter speed or exposure time in seconds) and ISO value (ISO setting) by rotating the respective controls.
The setting that has not been touched for the longest time, is marked with a green dot. This setting will continuously and automatically rotate to the value that best aligns with the current illumination measurement, to show a combination of settings for proper exposure.
If the automatic rotation cannot achieve a correct exposure, a red warning triangle will indicate the issue. In such cases, consider adjusting one of the settings to restore a well-balanced exposure.
While an exposure meter provides valuable guidance, achieving correct exposure involves more than just following it. Depending on factors such as backlight and the desired effects you might want in your photo, you may need to adjust the exposure in either direction.
The Exposure Picker can be easily hidden or shown. Simply click on its top-right corner to toggle its visibility.

How Accurate are the Measurements?
The app has undergone extensive testing on various devices from different brands and has been calibrated against three different professional light meters. But the accuracy will of course ultimately depend on the device/phone you are using the app on. It is also important to understand that slight variations in how you hold your device or conduct measurements can significantly impact the results. See the measurements as good approximations.
For relative measurements — comparing the illumination from different light sources with the same smartphone or tablet, utilizing the same camera or light sensor on the device — the results are extra reliable.

Why is the Scale so Strange?
The scale is logarithmic. A logarithmic scale aligns with how our eyes perceive and respond to changes in light, providing a more intuitive representation of the visual experience. Small changes in light intensity are more noticeable in lower light conditions than in brighter environments. Light intensity levels can vary widely, from extremely low levels in dimly lit environments to very high levels in bright sunlight. A logarithmic scale accommodates this wide dynamic range more effectively than a linear scale. It allows to represent a large range of values in a compact and manageable scale, making it easier to interpret and compare measurements across different lighting conditions.

Does the App Need Improvement?
If you have complaints, questions, or ideas for improvement, please contact me. I respond to all emails and am always interested in enhancing the app.
apps@contechity.com