Android camera2 API get focus distance in AF mode

Question

I'm working with Android camera2 API.

I can get focus distance value using LENS_FOCUS_DISTANCE in manual focus mode. However, the property is always zero in AF mode. Is there any way to get focus distance in AF mode?

Answer 1

If the value of LENS_INFO_MINIMUM_FOCUS_DISTANCE is 0, it means it is fixed focus and not supporting manual focus. Limited capability - Present on all camera devices that report being at least HARDWARE_LEVEL_LIMITED

Answer 2

Shortest distance from frontmost surface of the lens that can be brought into sharp focus.

If the lens is fixed-focus, this will be 0.

http://developer.android.com/intl/es/reference/android/hardware/camera2/CameraCharacteristics.html

In other way, if you want to manage focus, remember that LENS_INFO_MINIMUM_FOCUS_DISTANCE give you the minimum focus, but to get the "Max" focus you must use LENS_INFO_HYPERFOCAL_DISTANCE.

float yourMinFocus = mCameraCharacteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
float yourMaxFocus = mCameraCharacteristics.get(CameraCharacteristics.LENS_INFO_HYPERFOCAL_DISTANCE);

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For 2021 when using CameraX, here's how to find camera characteristics such as LENS_INFO_MINIMUM_FOCUS_DISTANCE:

theCamera = cameraProvider.bindToLifecycle(...
CameraCharacteristics camChars = Camera2CameraInfo
   .extractCameraCharacteristics(theCamera.getCameraInfo());
float discoveredMinFocusDistance = camChars
   .get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
Log.i("dev", "min focus is " + discoveredMinFocusDistance);