Photographic cameras were a development of the camera obscura, a device dating back to the ancient Chinese and ancient Greeks, which uses a pinhole or lens to project an image of the scene
outside upside-down onto a viewing surface.
Before the invention of photographic processes there was no way to preserve the images produced by these cameras apart from manually tracing them. The earliest cameras were room-sized, with space for one or more people inside; these gradually evolved into more and more compact models such as that by Niépce's time portable handheld cameras suitable for photography were readily available. The first camera that was small and portable enough to be practical for photography was envisioned by Johann Zahn in 1685, though it would be almost 150 years before such an application was possible.
What next?
Louis
Daguerre and Joseph Nicéphore Niépce (who was Daguerre's partner, but died before
their invention was completed) invented the first practical photographic
method, which was named the daguerreotype, in 1836. Daguerre coated a copper
plate with silver, then treated it with iodine vapor to make it sensitive to
light. The image was developed by mercury vapor and fixed with a strong
solution of ordinary salt (sodium chloride).
35mm
Reflex Camera
The first
practical reflex camera was the Franke & Heidecke Rolleiflex medium format
TLR of 1928. Though both single- and twin-lens reflex cameras had been
available for decades, they were too bulky to achieve much popularity.
Digital
Digital
cameras differ from their analog predecessors primarily in that they do not use
film, but capture and save photographs on digital memory cards or internal
storage instead. Their low operating costs have relegated chemical cameras to
niche markets. Digital cameras now include wireless communication capabilities
(for example Wi-Fi or Bluetooth) to transfer, print or share photos, and are
commonly found on mobile phones.
DSLR's
‘Digital single-lens reflex cameras’ are digital cameras
combining the optics and the mechanisms of a single-lens reflex camera with a
digital imaging sensor, as opposed to photographic film. The reflex design
scheme is the primary difference between a DSLR and other digital cameras. In
the reflex design, light travels through the lens, then to a mirror that
alternates to send the image to either the viewfinder or the image sensor. The
alternative would be to have a viewfinder with its own lens, hence the term
"single lens" for this design. By using only one lens, the viewfinder
presents an image that will not perceptibly differ from what is captured by the
camera's sensor.
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