Note that m = h¢/h where h is the size of the object and h¢ the size of
the image This is also the ratio of the angle subtended by the image
to that subtended by the object, if placed at D for comfortable viewing (Note that this is not the angle actually subtended by the object at the
eye, which is h/u ) What a single-lens simple magnifier achieves is that it
allows the object to be brought closer to the eye than D