It appears that the automated focus stacker shown in another thread on here achieves focus by moving the camera and lens closer or farther from the subject.
How does this affect the image scale and, if the change is objectionable, how is the different image scale handled? Does the focus stacking software automatically resize each image to keep image scale constant?
I downloaded the PDF books recommended by another user, but haven't read 'em yet. (Yeah, I know... RTFM).
I don't use the automated method, I manually move the plane of focus by moving the camera on a focusing rail. I believe the changes in scale are handled by the software. A related issue is when one uses this methodology for achieving greater focus in a landscape. This requires the focus point to be made by using the focusing ring on the lens. This change is image size must be done by cropping final stacked landscape. What this requires is planning the original images to be stacked to leave cropping room in those images. (Since I learned to "fill the frame" to maximize small negative/transparency size, this was an early mistake.) Hope this answers your question.