Macro Merging Photos

My friend in the Photo Club referred me to a freeware program that enables the photographer to take macro photographs that focus on particular parts of the subject that you want to appear in focus in the final product. Usually a macro photo places some parts in focus while leaving other key parts slightly out of focus. The software combines all the images taken and seamlessly connects them together to produce a superior end result. I am about to put this to the test.
When looking for the web site I also found this important information relating to Z.
The software is called "CombineZ"http://www.outbackphoto.com/workflow/wf_72/essay.html

23.1.3 Perspective z-Coordinate Transformations

The z value in eye coordinates, z_eye, can be computed from the window coordinate z value, z_window, using the near and far plane values, near and far, from the glFrustum() command and the viewport near and far values, far_vp and near_vp, from the glDepthRange() command using the equation:

The z window coordinate is computed from the eye coordinate z using the equation:

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