HOW DO I LAYER TWO PHOTOS?

You cannot layer photos in Aperture; you will need an external editor for that, e.g. GIMP or Photoshop. Aperture has not been designed to do compositing, sorry.

While it is true that Aperture does not provide support for compositing images directly within the application, Aperture can be used to make this job easier for third party applications that do support this functionality.

I'm currently working on a three part series on how to use Aperture to aid in creating focus stacks — i.e. a series of similarly composed but differently focused photos that are layered to create a single image where everything in the frame is in sharp focus. Parts one and two are complete and available on my blog, but it is part three that will get into the heavy lifting inside Aperture. Stay tuned...

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