Roll view while looking through camera

Question

I am painting grease pencil based on a fixed camera angle. The camera itself is locked and won't move. I am looking through it, but the camera is not locked to view, so I can still pan and zoom without moving the camera. It is projecting a background image that I am painting the grease pencil over. There are also 3D objects being painted over.

To make painting certain angles easier, i want to be able to rotate the canvas like you'd normally do in photoshop or SAI or Krita. But I can't find a way to do this while looking through a camera. In the Viewport camera, you can use shift+numpad 4 or 6 to roll it. This does not work when looking through a camera. If I unlock the camera and roll it, then my background image rotates with it, so that doesn't work.

I need some way to roll my view of the active camera without rotating the active camera itself. Is this possible?

Answer 1

As far as I know, if you rotate the camera, the background image will always rotate with it. However, similarly to this question, you can display the image inside of an empty instead of as a background image, and then you can roll your active camera, and the empty displaying the image won't move.

I realize that this isn't a perfect solution since using the empty isn't nearly as easy as just using the background image feature, but it's the best I can come up with.