When shooting a pic of a truck on a hill...don't point the camera at the truck with the lens even with the ground...because the eye makes the ground the reference point for what is level...

Take the pic with the camera level (Like hanging from a Plumb Bob, etc...), not even with the slope.

When the pic is taken with the camera truly level, the picture will show the true slope the X is on, instead of making it look like its on flat ground.



Try it out, the pics will show what you were REALLY getting the X to do.