TM5-6675-326-14
4-6.2.2 Operation - Continued
b .
Determine map lens power. Lowest power provides greatest
field of view; highest power provides greatest detail.
Photograph and
scale in order
c o r r e c t i o n s.
(1) Determine map scale
NOTE
map must be at same relative
to make accurate
and photographic
Example: 200 scale:
1 in. on map equals
cartographic
scale.
2 0 0 f t o f t e r r a i n.
1 i n. = 1 mi:
1 in. on map equals 1 mi of terrain.
RF 1:24,000:
Reduction factor of map.
1 in. of
map equals 24,000 in. of terrain.
( 2 ) D e t e r m i n e r e d u c t i on
Example:
200 scale = RF
1 i n. = 1 m i =
factor (RF) of both photograph and map.
1/2400:
1 in. on map equals 2400
i n . o n t e r r a i n ( 2 0 0 f t =
24 0 0 i n . ).
RF 1/63,360:
1 in. on map equals
63,360 in. on -
t e r r a i n . ( 1 m i =
5280 ft = 63,360
i n . )
(3) Determine matching scale S. Use RF of photograph as l/P
and RF of map as l/M.
Then the scale S can be expressed
as photograph reduction factor (P) over the map reduc-
t i o n f a c t o r ( M ).
S = l/M divided by l/P or S = P/M
Example:
Photograph RF = 1:80,000; Map RF = 1:24,000.
Thus, P = 80,000; M = 24,000; and
s = 80,000/24,000 = 3.3.
(4) Use the value of S to determine map lens and photograph
m a g n i f i c a t i o n:
S Value
Map Lens
Photograph Magnification
1-7
1X
1X-7X
2-14
1X
2X-14X
Example:
If 3.3 is the value of S, then map lens of 1X and
either 1X-7X attachment lens or 2X-14X (without
attachment lens) may be used.
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