After Effects treats a composition like it’s a piece of footage. Whatever camera and layers you have in your main comp will not be affected by anything in your precomp. It’s as if the precomp is just some .mov or .avi file you’ve dropped on the timeline.
The change happens when you push the “collapse transformations” button. Then any 3d layers you have in your precomp become 3d in the main comp. But, if I’m not mistaken, the camera in the precomp will be overridden by the camera in the main comp.
If you want to have the same movement in the main comp that you had achieved in the precomp you could just copy and paste (or maybe cut and paste) the camera from the precomp into the main one and retie the expressions to their respective nulls..
– The Great Szalam
(The ‘Great’ stands for ‘Not So Great, in fact, Extremely Humble’)
No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.