Employing a Common Main Objective [CMO] optical system, the K400 produces flat, crisp, and true color representations for the user over a long and continuous period. The CMO system benefits the user with the potential of accessory addition without sacrificing optical quality, which makes the K400 suitable for inspection applications. The various contrast methods offer endless expandability of the K400 without the need for purchasing a new microscope or modification. Therefore, one problem can be examined in two to three different methods with one microscope without the extra space required for another microscope. An ideal option for universities or laboratories with limited space.