Camera

A camera is a device that collects light from an object and records a visual image. The image can be recorded on chemical film or an electronic sensor that converts light into digital information.

The basic structure consists of a light-tight box, a lens that gathers light, an adjustable aperture, and a shutter that controls how long light enters the device. The interplay of these three elements determines exposure, depth of field, and how motion is captured.

Brief history

The concept derives from the camera obscura—a dark room or box with a small opening that projects an inverted image of the outside scene onto a surface opposite the opening. In the 19th century, chemical methods were developed to permanently fix such images, marking the beginning of modern photography.

During the 20th century film became widespread, particularly in 35 mm format. From the late 20th century into the early 21st century, digital sensors largely replaced film for general use, and mobile phones became the most commonly used image-capture device.

Types

There are simple cameras for straightforward use, reflex cameras (SLR/DSLR) where the photographer sees what the lens sees, mirrorless cameras, and cameras designed to record motion as film or video. Specialist cameras also exist for scientific research, medical imaging, and astronomy.

Exposure control

A properly exposed image depends on three interrelated factors: aperture size (f-number), shutter speed, and the sensitivity of the sensor or film (ISO). When one is adjusted, the other two are typically modified to maintain consistent exposure.