How Can I Monitor The Current Focallength Of Android Camera

I have a SurfaceView that holds a Camera Preview. I have set the camera focus mode to: Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO and added an AutoFocus callback. When i run t

Solution 1:

Maybe you are confusing two different concepts: focus distance and focal length.

It seems you are interested in the focus distance, i.e. the distance for which the optical system has perfect focus; this depends on how far or close you are from in focus objects.

On the contrary, the focal lengthis an intrinsic property of the optical system (i.e. of the camera lenses), and it is fixed in most standard mobile devices (optical zoom capabilities are needed to have a variable focal length). The value you get, 2.95, is the focal length (in mm) of your camera. Nexus 7 2013 tablets have such focal length.

Thus, it is perfectly normal that the function getFocalLength() always gives you the same value.

Solution 2:

Most Android implementations do not provide a proper value for the focus distance, despite the parameter being well-defined in the Android specification. Some time ago, I checked three different cameras, and none of them provided useful information.