Im a little confused about doing the simple ball bounce down stairs exercise. i thought you drew the stairs out in every frame. However I was talking to some one who said you didnt and you just edit it after on a diffrent layer if that make sense.
Anyone know the right way to do it?
Usually you have background art which would have the stairs, and that would stay there for the whole shot. So you don't have to keep re-drawing the stairs for every frame, you only have to draw them once. The animated character would be on a layer above that (a clear acetate cel, in the old days, or a layer in animation software today) and would be changed from frame to frame. Some of the time you would get away with moving the drawing of the ball, but when it squashes and stretches you would re-draw it.
I recommend reading a good book on animation - my personal favorite being the Animator's Survival Kit by Richard Williams. Animation technically began with stopmotion - as a trick photography technique just to make things seem to appear and disappear in an otherwise live action film back in early silent movie days, but then drawn animation quickly became a thing and in fact was where all the innovation and evolution took place. It's incredibly enlightening to read about how it happened, and greatly enhances your overall understanding of filmmaking and animation and how they function together.
I just realized what you might be thinking of. There is a certain kind of 'funky' drawn animation style where the animator will re-draw the background - at least 2 or 3 frames of it - so it sort of pulsates. This is often done in those little cartoon segments on the beginning of certain indie films - I think it was used in Juno? Not sure. But even then the animator wouldn't usually re-draw the entire background for every frame - that would take forever! This kind of technique would only be done for the most minimalist drawing style, where everything is drawn in the simplest way possible.
I'm talking about this kind of animation:
This one is by Bill Plympton, one of today's best-known animators in this primitive style. And he actually does re-draw every frame, and last time I checked, he did everything himself - no in-betweeners to draw all the tedious frames that the key animator didn't need to do.
Here's a trailer for one of Plympton's films - I see he's not always re drawing the backgrounds anymore:
You can easily tell when he does and when he doesn't - if everything looks completely different from one frame to the next it's been redrawn, but often now he just uses a single background plate and slides it or zooms in on it from frame to frame. It creates a very different kind of look -more in line with what you expect from modern studio animation as opposed to his usual completely hand drawn approach.
I'm a fan of Plympton's style. I have one of his hand-drawn frames from Cheatin'