Advanced Photography Course

Figure 4-21.--Number of flight lines nomograph.

is 1/10,000, the distance between flight lines drawn on
the chart is 64,800

1/20,000, or 3.24 inches. Since it

is difficult to measure the flight-line distances
accurately, a multi-finger divider should be used (fig.
4-22).

To use the multi-finger divider, first multiply the

distance between flight lines by the number of fingers
on the divider. This will give you the total flight-line
plot width. Using a ruler, place the first divider finger
on zero and the last divider finger on the mark
corresponding to the total flight-line plot width. The
individual fingers of the divider automatically space
themselves to the correct distance for each flight line.

The multi-finger divider may then be used to lay out the

flight-line plots.

INTERVAL BETWEEN EXPOSURES

You must convert the aircraft ground speed to feet

per second to determine the exposure interval or
frequency between frames. The conversion factor for

Figure 4-22.--Multi-finger divider.

4-23

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Advanced Photography Course

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