The awesome openexr format. You can just save all your render passes right into this image format and access them in post, if your software supports it .  Experiment a little using photoshop and after effects in combination with the fabulous proexr plug-in, which also offers a nice add-on to automate the creation of the composition layers in after effects. check out the manufacturer’s manual, it’s worth reading it; also to learn more about this image file format in more depth.