A small depth of focus is very often a problem in the conventional high resolution light microscopy, because the objects are higher than the depth of focus. The connections of conventional light microscopes, video techniques and computers open new fields of applications for microscopy. It is possible to generate an image containing focused areas from a series of images of different focus- or z-positions. In this way it is possible to extend the depth of focus without a physical limitation of the numerical aperture (NA) of the objective lens. The connection of microscope, video and PC opens also the field of high resolution low light color applications, like fluorescence in situ hybridization (FISH). Image processing technology enables the enhancement of contrast for objects with a very low contrast. And such a system opens also the way to view objects with small motions, like processes of growing of biological objects. It is also the elimination of the limits in the X/Y-direction by a full color mosaics (patchwork mode) with a resolution up to 4500 by 3500 pixels. The last step in the development of the system was the generation of short movies of different 2D projections of the 3D data cube showing the spatial structure of the objects. It is possible to display up to 15 true color RGB-images per sec with a resolution of 664 by 512 pixels. Now the system is a powerful tool to generate image you never can see through the eyepieces.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.