I seldom use the Auto function on my camera unless I'm doing street photography (it's called path photography here). This rainbow appeared out of nowhere ? so I grabbed the camera, switched it to Auto and took a quick shot. I then switched to M, set the WB, ISO, Tv and Av. When I went to set the focus, the rainbow was gone. Those exposure values listed are not what I had chosen. I'm not sure I like the idea of having a camera that's smarter then I.

Canon EOS M10
50mm, f8
1/200s, ISO100