The object to be magnified is placed just beyond the focus of the objective lens. A real image is then formed between the two lenses as shown, which acts as an object for the eyepiece lens. The real image is virtual, inverted and magnified.
The magnification is the product of two factors. The magnification produced by the object lens is
where
and
ate object and image distance respectively. The magnification produced by the eyepiece is
0.25m is the near point of the eye – the closest an object can get to the eye and still be properly resolved. The overall magnification is the product of these two factors:
