Light Meter for Photography is an Android app developed by appdev that allows you to use your phone as an incident light meter. With this app, you can measure F number, shutter speed, or ISO sensitivity and set these values on your camera. The app uses incident light to measure exposure, making it more accurate than built-in reflective exposure meters found on digital cameras. It can also be used to take pictures with classic cameras that don't have an exposure meter.

To use the app, simply point your Android phone, which is running the app, in front of your subject and towards your camera. Press the "MEASURE" button to start measurement and again to finish it. The app will record the measurement value, which you can use to set the shooting conditions on the app. Once set, turn on your camera to manual mode and set the ISO/F/SS values displayed on the app to your camera. Then you can shoot with your camera.

Overall, Light Meter for Photography is a handy app for photographers who want to achieve accurate exposure, especially in challenging lighting conditions.