Nomenclature, Foreword, Fisheye lens – Nikon Fisheye-NIKKOR 8mm f-2.8 User Manual

Page 10

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8 EE Servo Coupling Post

9 Aperture-Direct-Readout Scale

10 Aperture Indexing Post

11 Meter Coupling Ridge

12 Aperture Ring

NOMENCLATURE

1 Aperture Index

2 Distance Scale

3 Distance Index

4 Focusing Ring

Filter Selector Dial

5 Aperture Scale

7 Meter Coupling Shoe

FOREWORD

The Fisheye-Nikkor 8mm f/2.8 lens sees and records every object in a full

180° hemisphere—everything in front, above, below and to either side of the
lens. Unlike other fisheye lenses, it fits the camera without any need to lock

up the reflex mirror and takes full advantage of the reflex viewing feature of
all Nikon cameras. The focusing range extends down to one foot to permit

pinpoint focusing on foreground objects while throwing the background out

of focus at large apertures, and the aperture diaphragm couples with the

TTL exposure meters for full-aperture exposure measurement. The wide

maximum aperture of f/2.8 means that the viewfinder image is extra-bright
for easy viewing and focusing even in dim light. A set of five filters is built

into the lens barrel.

FISHEYE LENS

Like most fisheye lenses, the Fisheye-Nikkor 8mm f/2.8 covers a 180° hemi

sphere and produces a circular image on film. Barrel distortion is consider

able, since the circumference of the image circle corresponds to a straight

line.

The equidistant projection formula (y=C0) is used in order to accommodate

this extra-wide picture angle within a field of finite size,The zenith angle

( 6 )

of any point in the image recorded on film is proportional to the distance

(y) from the center of the image (see Photogrammetry, Page 12).

Originally designed for scientific applications such as measuring the zenith

or azimuth of astronomical bodies, recording cloud distribution patterns in

the entire sky or surveying by photogrammetry, the lens is also suited for

many other unique requirements. It is used widely for creating special ef

fects, photographing the insides of inaccessible spaces, recording crowd
movements in large areas, etc.