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No classification method can include all cameras
- Jul 10, 2018 -

There are a wide variety of cameras, which can be divided into landscape camera, print plate camera, document micro camera, micro camera, underwater camera, aerial camera, high speed camera, etc. according to the purpose; according to the size of the film, it can be divided into 110 cameras (picture 13× 17 mm), 126 camera (picture 28 x 28 mm), 135 camera (picture 24 x 18, 24 x 36 mm), 127 camera (picture 45 x 45 mm), 120 camera (including 220 camera, picture 60 x 45, 60 x 60, 60 × 90 mm), disc camera (picture 8.2 x 10.6 mm); divided into a fluoroscope camera, a dual-lens reflex camera, and a single-lens reflex camera according to the framing method.

No one can include all cameras. There are several categories for a camera. For example, 135 cameras differ in their viewfinder, shutter, metering, film, exposure, flash, focus, and self-timer. It constitutes a complex spectrum. The camera uses the linear propagation properties of light and the law of refraction and reflection of light, and uses photons as a carrier to transmit the amount of light information of a scene at a certain moment to the photosensitive material through the photographic lens, and finally becomes a visible image. The camera's optical imaging system is designed according to the principle of geometric optics, and through the lens, the scene image is accurately focused on the image plane by linear propagation, refraction or reflection of light. When photographing, it is necessary to control the appropriate amount of exposure, that is, to control the amount of photons that reach the photosensitive material. Because the amount of photon received by the silver salt photosensitive material has a limited range, the amount of photons is too small to form a latent image nucleus, and the amount of photons is too much to form an overexposure, and the image cannot be distinguished. The camera uses the aperture to change the aperture of the lens to control the amount of photons that reach the photosensitive material per unit time. At the same time, the opening and closing time of the shutter is changed to control the length of the exposure time.

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