17.
What are the three factors controlling circles of confusion?
_________________________________________ _____________________________________,
,
_________________________________________
.
2-14. CONJUGATE DISTANCE.
a.
The distance between a subject and a photographic lens varies
inversely with the distance from the lens to the focal plane.
These
distances are called conjugate distance; that is, the total distance from
the subject to the focal plane, (fig 2-20).
Figure 2-20.
Conjugate distance.
b.
When we say that these distances vary inversely, we mean that one
distance increases as the other decreases, and vice versa.
In other
words, when the lens-to-subject changes, the lens-to-film distance must
change.
When the lens-to-subject distance increases, the lens-to-film
distance decreases, (fig 2-21a).
Similarly, if the lens-to-subject
distance decreases, the lens-to-film distance will increase, (fig 2-21b).
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