OKO Light Meter is a free Android app developed by okacat that helps photographers determine the correct exposure for their photos. The app uses your phone's built-in light meter to measure the amount of light in your surroundings and provides you with accurate information to adjust your camera's settings.

One of the best features of OKO Light Meter is its ability to lock the measured value with the volume down key on your device and unlock with volume up. This makes it easier to adjust your camera's settings without having to constantly refer back to the app. Additionally, the app supports setting the ISO value and measuring for shutter speed or aperture.

However, it's worth noting that device sensors are usually not accurate enough for low light situations. In these cases, OKO Light Meter provides descriptive presets to help you determine the amount of light. Overall, OKO Light Meter is a great tool for photographers who want to capture high-quality photos with accurate exposure.