Why are some of my pictures all black? I was out on a hike today and took a few pictures. When taking a picture I saw the usual animation where I see snapshot of the picture just taken, and then it slides away from the screen to display the camera viewfinder again. After coming home I notice this in my google photos: 

What causes this to happen?
It appears as if this is an issue where the camera got activated in a dark place, such as your pocket. Undue pressure (false touches) can cause this, or even if the camera app took 2 pictures in burst mode (it isn't supposed to happen, but it does anyway). There can also be other issues which may rarely be for to a hardware problem, but since this is not a major problem I don't think it merits a service center visit.