The T490B features a unique "simul-focal" optical system with an adjustable trinocular port to enable well-focused clear images on your PC or video screen while simultaneously obtaining sharp, focused images through the eyepieces. Most trinocular microscopes allow you to view either through the trinocular port or the eyepieces only, forcing you to switch between the two. Since these trinocular ports are not "simul-focal" with the rest of the microscope optical system, you have to re-focus the microscope after each switch. The T490A, however, erases this step by providing "simul-focal" viewing. Especially handy for teaching demonstrations, clinical examinations and laboratory applications, the "simul-focal" feature allows your students or colleagues to view clear images simultaneously while you work through the eyepieces. In addition, the T490A's industry standard 23mm photo port can be converted into a C-Mount port by attaching the included C-mount adapter, allowing you to attach most microscope digital cameras and video systems on the market.The T490A includes a 30-degree inclined 360-degree swiveling trinocular Siedentopf head, a 3-D mechanical stage, and an intensity-variable halogen illumination system. This versatile microscope is also capable of being upgraded with various accessories and attachments listed in the optional section for additional functions. It is a perfect laboratory instrument for clinics, Vets, Doctors, and professional students. Made by the same OEM supplier that provides optical instruments for Leica, Zeiss, Nikon and Olympus, it arrives brand new in a factory sealed box and retails for more than $1,700.