I have created a painting with too many layers in Photoshop. I'd like to add motion to it and make a simple animation using Photoshop timeline. Is it possible to add a motion one time and extend it to several groups of layers in order to zoom them all in and out simultaneously? It is so hard to add the same motion to all layers separately.
It seems it can't be done easily via photoshop!
=> well i won't say it is impossible at all in photoshop but the thing I'm saying is that photoshop doesn't seems have native implementation of many features when it comes to animation (since photoshop is photo editing tool and added animating capabilities only as feature) it have many restrictions but I've came with plugin named Animatior's Toolbar Pro a very far ago and it seems it might have the thing you want! so I think it can be done via photoshop scripting in very deep level!
=> but rather making some script like that level; I'll recommend you to make animations via some free animation tools like Dragon Bones or free trials of After Effects or any other kind of animation tools which specially made on principles of animation! Happy Animating!