The optical lenses used in compound microscopes can be classified into two eyepiece and objective lenses. The single lens or multiple set of lenses located the top of the lens is known as the eyepiece. The eye piece can have a fixed or a variable magnification which is usually in the range of 5 - 30x.
The set of lenses at the bottom of the eyepiece tube near the specimen being observed are known as the objective lenses. They come in sets with varying magnifications that can be adjusted based on what is being observed. Objective lenses have a magnification of 4-100x
The two sets of lenses give compound microscopes an ability to magnify from 20x - 3000x.
The occular lenses of the eyepiece and the interchangeable objective lenses between the eyepiece and the stage.
Standard achromatic lenses help prevent color distortion. Semi-plan or plan lenses improve image quality through superior clarity and flatness. Super High Contrast lenses offer extra image contrast so that the image appears much sharper.
Plan Lens: The finest objective lens that "flattens" the image of the specimen and greatly enhances the resolution and clarity of the image.