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PHOTOGRAMMETRY
The circular photographic image produced by the Fisheye-Nikkor 6mm f/2.8
is an exact reproduction on a flat plane of all objects within the 220°
field.
This feature enables the lens to be used in locating astral bodies or recording
cloud distribution. The center of the image corresponds to the zenith in the
angle of view, and the distance of any point in the image from this center is
directly proportional to its angle from the zenith, expressed by the equation
y = CO, where y is the distance of the point from the image center, 6 is the
zenith angle, and C is a constant (see below). For example, a point jn the
image 4mm from the center represents an object at an angle of 37.2 from
the zenith in the angle of view. The table below gives zenith angles for
points at given distances from the center of the film image.
Relation of Zenith Angle to Distance of Point from Image Center
6 : Zenith angle
y : Distance of point
from image center
y
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
8°
0.000
4.615
9.241
13.873
18.514
23.165
27.829
32.510
37.210
41.929
46.669
51.431
56.214
61.019
65.845
70.690
75.553
80.429
85.317
90.216
95.129
100.069
105.061
110.155
A0°
4.615
4.626
4.632
4.641
4.651
4.664
4.681
4.700
4.719
4.740
4.762
4.783
4.805
4.826
4.845
4.863
4.876
4.888
4.899
4.913
4.940
4.992
5.094
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