24 shows that the (linear) magnification due to
the objective, namely h¢/h, equals
O
o
h
L
m
h
f
′
=
=
(9 43)
where we have used the result
tanβ = 


 =
′


fh
h
L
o
Here h¢ is the size of the first image, the object size being h and fo
being the focal length of the objective The first image is formed near the
focal point of the eyepiece The distance L, i