To provide a method of forming and using a virtual microscope slide.

The virtual microscope slide includes images of a specimen 31 for a given level of optical magnification which are associated and stored in a data structure. The forming of the data structure having the multiple Z-plane images includes a step of automatically focusing at a principal reference focal plane, a step of capturing and digitizing an optically magnified reference Z-image, and a step of shifting the specimen 31 relative to the lens system 15 by a predetermined increment to capture and digitize another Z-plane image. Thus, the resultant images are retrieved and displayed 40 such that a virtual focusing capability 12 is available to the user.