Lenses of various magnifications can be adapted to the carrier and moved about over the stage.
They are often so small that high magnifications may be necessary to ascertain their presence.
Small German periscopes were usually 1 metre or 2 a metre in length and had two eyepieces giving magnifications 10 and 15 diameters.
There are " chromatic differences " of the distances of intersection, of magnifications, and of monochromatic aberrations.
From this it appears that each observer obtains specific advantages from one and the same simple microscope, and also the individual observer can obtain different magnifications by either using different accommodations, or by viewing in passive accommodation.