But isn't the problem with isolating parts of the image at the optical level that you can't later undo it? It seems like at least one of the advantages to every

But isn't the problem with isolating parts of the image at the optical level that you can't later undo it? It seems like at least one of the advantages to everything being in focus is that you can isolate whatever you want in post-processing. Cameras are already doing this, they just require multiple lenses and thus more space and material to do it.