Photosensitivity in the context of "Camera lens"

A photograph (also known as a photo, or more generically referred to as an image or picture) is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor. The process and practice of creating such images is called photography.

Most photographs are now created using a smartphone or camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would perceive.

A film base is a transparent substrate which acts as a support medium for the photosensitive emulsion that lies atop it. Despite the numerous layers and coatings associated with the emulsion layer, the base generally accounts for the vast majority of the thickness of any given film stock. Since the late 19th century, there have been three major types of film base in use: nitrate (until about 1951), acetate, and polyester.

A camera obscura (pl. camerae obscurae or camera obscuras; from Latin camera obscūra 'dark chamber') is the natural phenomenon in which light passing through the small hole of a dark chamber or box will project an image of a scene outside the chamber (box) onto the surface opposite to the hole, resulting in an inverted (upside down) and reversed (left to right) projection of the view outside.

Camera obscura refers to analogous constructions such as a darkened room, box or tent in which an exterior image is projected inside or onto a translucent screen viewed from outside. Camera obscuras with a lens in the opening have been used since the second half of the 16th century and became popular as aids for drawing and painting. The technology was developed further into the photographic camera in the first half of the 19th century, when camera obscura boxes were used to expose light-sensitive materials to the projected image.

The retina (from Latin rete 'net'; pl. retinae or retinas) is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera.

The neural retina consists of several layers of neurons interconnected by synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rods and cones. Rods function mainly in dim light and provide monochromatic vision. Cones function in well-lit conditions and are responsible for the perception of colour through the use of a range of opsins, as well as high-acuity vision used for tasks such as reading. A third type of light-sensing cell, the photosensitive ganglion cell, is important for entrainment of circadian rhythms and reflexive responses such as the pupillary light reflex.

In photography, a shutter is a device that allows light to pass for a determined period, exposing photographic film or a photosensitive digital sensor to light in order to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as seen in a movie projector or a signal lamp. A shutter of variable speed is used to control exposure time of the film. The shutter is constructed so that it automatically closes after a certain required time interval. The speed of the shutter is controlled either automatically by the camera based on the overall settings of the camera, manually through digital settings, or manually by a ring outside the camera on which various timings are marked.