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The crystalline lenses of fishes' eyes are extremely convex, almost spherical, and their refractive indices are the highest of all the animals. These properties enable proper focusing of the light rays and in turn proper image formation on the retina. This convex lens gives the name to the fisheye lens in photography. [6]
In a circular fisheye lens, the image circle is inscribed in the film or sensor area; in a diagonal ("full-frame") fisheye lens, the image circle is circumscribed around the film or sensor area. This implies that using a fisheye lens for a different format than it was intended for is easy (as opposed to a rectilinear lens), and may change its ...
Due to refraction at the air/water boundary, Snell's window compresses a 180° angle of view above water to a 97° angle of view below water, similar to the effect of a fisheye lens. The brightness of this image falls off to nothing at the circumference/horizon because more of the incident light at low grazing angles is reflected rather than ...
Knowledge of surface ocean currents is essential in reducing costs of shipping, since traveling with them reduces fuel costs. In the wind powered sailing-ship era, knowledge of wind patterns and ocean currents was even more essential. Using ocean currents to help their ships into harbor and using currents such as the gulf stream to get back ...
Particle size effects how much scattering happens at different colors; for example, very small particles scatter light exponentially more in the blue colors than other colors, which is why the ocean and the sky are generally blue (called Rayleigh scattering). Without scattering, light would not “go” anywhere (outside of a direct beam from ...
Marine currents can carry large amounts of water, largely driven by the tides, which are a consequence of the gravitational effects of the planetary motion of the Earth, the Moon and the Sun. Augmented flow velocities can be found where the underwater topography in straits between islands and the mainland or in shallows around headlands plays a major role in enhancing the flow velocities ...
Ocean currents moving in the magnetic field of the Earth also generate electric fields that sharks can use for orientation and possibly navigation. [26] Among teleosts, the electric catfish uses electroreception to navigate through muddy waters. These fish make use of spectral changes and amplitude modulation to determine factors such shape ...
Usually, light enters through the fish eye at the cornea and passes through the pupil in order to reach the lens. Most fish species have a fixed size of the pupil while a few species have a muscular iris that allows for the adjustment of the pupil diameter. Fish eyes have a more spherical lens than other terrestrial vertebrates.