Optical and digital microscopes produced by wikipedia

  A primary difference between an optical microscope and a digital microscope is the magnification. With an optical microscope the magnification is found by multiplying the lens magnification by the eyepiece magnification. Since the digital microscope does not have an eyepiece, the magnification cannot be found using this method. Instead the magnification for a digital microscope is found by how many times larger the sample is reproduced on the monitor. Therefore the magnification will depend on the size of the monitor. The average digital microscope system has a 15" monitor, would result in an average difference in magnification between an optical microscope and a digital microscope of about 60%. Thus the magnification number of an optical microscope is usually 60% larger than the magnification number of a digital microscope.
  Since the digital microscope has the image projected directly on to the CCD camera, it is possible to have higher quality recorded images than with an optical microscope. With the optical microscope, the lenses are made for the optics of the eye. Attaching a CCD camera to an optical microscope will result in a image that has compromises made for the eyepiece. Although the monitor image and recorded image may be of higher quality compared with the digital microscope, the application for the microscope may dictate which microscope is preferred.