The function of the lens or simply the eye glasses is to allow the eye to focus to a single positive converging lens which is used close against the object near than the least distance of comfortable vision. In a simple microscope, consider that the E stands for the eye, L for the without the aid of the lens thus, for clear vision the maximum angle is subtended at the eye by an object when it is placed at I. The subtended angle alpha would be larger. However the vision would not be clear because MI is the least distance for comfortable vision. The popularly known magnifying glass or reading lens which is classified as simple microscope is an instrument used for viewing close small objects with a single optical system. With the aid of the lens and MI stands for the least distance of comfortable vision.

The eye cannot see clearly an object lens the object would appear distinct and magnified. In a simple microscope, when the magnification is greater the focal length would be lesser. However since the curvature of the surface increases, the focal length of length of lens also increases. The limitation would be if is not possible to obtain a lens of a very small focal length thus as a result, large magnification cannot be obtained in a simple microscope. Simple microscope has a great help to scientists, doctors, students and other medical practitioners because of the nature of their works. With the use of such simple microscope, students gained knowledge from easier viewing, allowing their projects and assignments be done easily like during experimentation. But the disadvantage of a simple microscope is that, large magnification cannot be viewed due to small focal length. Over all, let us be thankful of the discovery of simple microscope, because it is the beginning of new discoveries for improved microscopes.