The camera obscura is an optical device that projects an external image onto a screen in a darkened space. The earliest reference to the pinhole camera, a precursor to the camera obscura, was by the Chinese philosopher Mo-Ti in 470 BCE. A digital camera records still images or video digitally using an electronic image sensor, allowing images to be immediately viewed, stored in large quantities, and deleted to save space. Point-and-shoot cameras automate all camera settings but have limited control, while DSLR cameras allow manual control and interchangeable lenses for more advanced photography. Demand for digital cameras, especially DSLRs, has grown due to technological advances, lower prices, and interest in emerging markets.

1. By Arpan Chakraborty

2. The camera obscura (Latin; "camera"
is a "vaulted chamber/room" +
"obscura" means "dark"= "darkened
chamber/room") is an optical device that
projects an image of its surroundings on
a screen.

3. The first mention of the principles behind the
pinhole camera, a precursor to the camera
obscura, belongs to Mo-Ti (470 BCE to 390 BCE),
a Chinese philosopher and the founder of Mohism
.[1] Mo-Ti referred to this camera as a "collecting
plate" or "locked treasure room".[2] The Mohist
tradition is unusual in Chinese thought because it
is concerned with developing principles of logic.

7. A digital camera (or digicam) is a camera that takes video or still
photographs, or both, digitally by recording images via an electronic
image sensor. Most 21st century cameras are digitalDigital cameras
can do things film cameras cannot: displaying images on a screen
immediately after they are recorded, storing thousands of images on a
single small memory device, and deleting images to free storage space.
The majority, including most compact cameras, can record moving
video with sound as well as still photographs. Some can crop and stitch
pictures and perform other elementary image editing. Some have a
GPS receiver built in, and can produce Geotagged photographs

8. Point and shoot cameras mean just that, point the camera at
something and trip the shutter. The camera does all the work for you.
Unfortunately, the camera is rarely as smart as the photographer so
the results can be iffy. Point and shoot cameras are often abbreviated
as P&S. These cameras started out as a fixed lens that focused about 4
feet in front of the camera with a fixed aperture and shutter speed. It
was basically a box with a shutter. Then the lab that developed the film
did what it could to fix the exposure. Today's P&S cameras are much
more sophisticated.

9. SLR stands for Single Lens Reflex and DSLR stands for Digital Single Lens
Reflex and refers to how the light enters the camera. These are the cameras
you see many professionals and serious amateurs lugging around. These
cameras have a larger body than most P&S cameras and interchangeable
lenses. While SLRs started out a fully manual, where the photographer had to
control all features including focus, most of these cameras are capable of
acting in a fully automatic mode just like a P&S. Many now allow the
photographer the freedom to also take control of all functions or any
combination of functions. These cameras allow for great control over the
photography process and allow the photographer to take images not always
possible with a P&S.

10. The demand for digital cameras has presented a strong outlook,
including cameras fitted in devices such as mobile phones and
showed a positive response even in the economic downturn, during
2008 & 2009. Technological advancement has helped the growth of
various consumer electronics products, digital cameras being one
of themSLR accounted for the highest growth rate in 2009, driven by
growth in Asia, especially in China. The potential for growth of
digital SLR cameras is very high because of technological
innovations, portability, falling prices and rising interest of teens.
The growth rate has slowed down in Japan and the US, while it has
increased in the emerging regions of China, India and Eastern
Europe Demand for Digital cameras and SLR has been mainly
driven by demand in emerging markets (China, Russia), rising
internet usage and favouring disposable income.