New issue 844: ProjectionCamera not in right-handed orientation https://bitbucket.org/yt_analysis/yt/issue/844/projectioncamera-not-in-right...
It appears that the ProjectionCamera is not in the right-handed orientation like the PlotWindow objects are. You can see this in the docs here:
The 'off_axis_projection' calls ProjectionCamera, which yields an image with the disk horizontal, although in the next script the exact same L and north_vector are used but with OffAxisProjectionPlot, which yields an image with the disk vertical. I know the camera is getting rewritten right now, so this may change, but I just wanted to list it here in case this issue wasn't resolved after the scene PR.