@animator Hmm 
I’m not sure how to explain myself better so it’s easy to understand.
Pencil2D has a theoretically infinite canvas and on top of that sits a virtual object we call the camera
It’s like having a large sheet of paper worth of space to draw, but you will only be allowed to show what is seen by the viewfinder.
The camera object is the grey colored veil with a literal hole to allow you to “capture” the scene you’re painting.
In Flash terms, you’re basically always drawing on the pasteboard and the camera visible area acts as the traditional canvas which in turn determines what is seen in the final video output.
But let me be clear that there is no actual canvas like in flash. Instead you have the output size for the video determined by the camera viewfinder size. Which you can change by double clicking the camera layer.
If you select the camera layer (yellow) and then turn the layer OFF by pressing the circle to the left of the layer name. You will see everything turns white except your background or drawing. This means you’re now seeing “under” the camera, the entire unrestricted paper sheet, but when you are going to export a movie, you will only get a portion of that paper sheet on video.
Lastly, we have a simple visual guide with some animated GIF’s of how the camera behaves as well: