NOMENCLATURE
1 | Distance Scales | 7 | Meter Coupling Ridge |
2 | Distance Index | 8 | Aperture Indexing Post |
3 | Aperture Index | 9 | Aperture Ring |
4 | Aperture Scale | 10 | Filter Selector Dial |
5 | Meter Coupling Shoe | 11 | Focusing Ring |
6 | Aperture-Direct-Readout Scale | 12 | Base |
FOREWORD
The Fisheye-Nikkor 6mm f/2.8 lens has the widest picture angle of any lens on the market-an amazing 220 degrees. It records not only everything in front, above, below and to either side of the lens but also sees slightly behind itself. Multilayer coating reduces reflection, thus minimizing flare and ghost images. This results in improved contrast and excellent color rendition. 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 Nikon and Nikkormat cameras.The focusing range extends down to 0.9 foot to permit pinpoint focusing on foreground objects while throwing the back- ground out of focus at large apertures, and the aperture diaphragm off/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 LENSES
The usual fisheye lens covers a 180° hemisphere and produces a circular image on film. Barrel distortion is considerable, since the circumference of the image circle corresponds to a straight line. The Fisheye-Nikkor 6mm f/2.8 captures an extra 40° of picture angle and records the scene with varying degrees of distortion in the form of a circular image 23mm in diameter.
Like other fisheye lenses, the Fisheye-Nikkor 6mm f/2.8 applies the equi- distant projection formula (y = Cd) in order to accommodate the extra-wide picture angle within a field of finite size. The zenith angle of any point in the image recorded on film is proportional to its distance from the center of the image (see Photogrammetry, page 14). This makes the lens suitable for scientific requirements such as measuring the zenith or azimuth angles of astronomical bodies or recording cloud distribution patterns in the sky. It is also useful in surveying work which requires checking the camera position. And its extra coverage makes possible more accurate measurements of greater detail over the 180° field. The lens is also widely used for creating unique special effects.
