46 PHOTOGRAPHIC FACTS AND FORMULAS 
If T is The angle 
less than is less than 
0.4 25° 
0.45 25" 
0.5 Nn ae 
0.55 fo 
0.6 334° 
0.65 36° 
0.7 39° 
0.75 414° 
0.8 44° 
0.85 4614° 
0.9 4814° 
0.95 sh ey 
1.0 Bo. 
1} 58° 
12 G2" 
1.3 66° 
1.4 70° 
Site 74° 
1.6 77° 
He as 
less than 
1.9 
2.0 
2.1 
The angle 
is less than 
87° 
To determine the covering angle, the diameter is taken as 
equal to twice the distance from the principal axis of the lens 
to the farthest corner of the plate. 
angle, we take simply the diagonal of the plate as the diameter. 
The diagonals of ordinary plates and films are: 
24,x3%....4.0 in. 
24%x44%....49 in. 
$144x3%4....4.6 in, 
3% x4%....5.3 in. 
34% x5Y%....64 in. 
HOTS. th: MAE © Bee BE 
434 x 614....8.0 in. 
5 
5 
O72 
8 
10 
16 
20 
To determine the view 
RA 
x 7% 
hes ean 
x10 
m2 
x 20 
x 24 
oa) Ola 
S30.) 0a 
107 ae 
..  LZeuee 
RN Bs) cy. 
.. 200i. 
. ole ie 
