Criminological or comparator scopes are really two scopes that allow the superimposition of specimens so as to compare them, for example bullets or finger prints. A student microscope does not need to be nearly as sophisticated. However, many microscopes provided to high-school and introductory university students are so simple as to be useless. For example, a common introductory biology lab asks the student to examine the large chromosomes in the root-tip of an onion. That is impossible with many of the teaching microscopes that are used.
Students can become very frustrated.
The reason lies not with the power of the microscope, but with the illumination provided. To get a good image, regardless of the power, the specimen must be properly illuminated. The condensor serves to focus light on the specimen. Without it it is impossible to properly illuminate the specimen and get a satisfactory image. One sees too much diffuse, scattered light.