f=150 mm —L—7 N—L— —T [ 1 pu 1:36000 
  
\ 
/ N 
f=90 mm 1: 60000 
N 
x ~ 
N 
  
Fig.20 The diagram shows the advantage of the far-reaching 120° super wide angle lens compared with the usual 
90? lens. 
Fig. 21 From the same flight height, the 120° lens covers an area almost three times that covered by the 90° lens. 
  
  
  
f = 150 mm ; 1:36000 
f= 90mm 1:60000 
E x 
8 > 
wv x 
i X 
= 
13500 m 
ut 
| Fig. 22 
8100 m | To attain the same image scale it is necessary 
T m | to fly higher,in the ratio 5:3, withthe 90?lens as 
| compared with the 120° lens. 
N 4 f=150 mm 
| AN 
| 5 
F | d 
| NC LA 
| NN \ f=90 mm 
ZX \ \ 
| 3 ^ N 
r~ IF | / r SN \ 
16