Cameras
Camera
A camera is a device that records images, either as a still photograph or as moving images known as videos or movies. The term comes from the camera obscura (Latin for “dark chamber”), an early mechanism of projecting images where an entire room functioned as a real-time imaging system; the modern camera evolved from the camera obscura.
Cameras may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum. A camera generally consists of an enclosed hollow with an opening (aperture) at one end for light to enter, and a recording or viewing surface for capturing the light at the other end. A majority of cameras have a lens positioned in front of the camera’s opening to gather the incoming light and focus all or part of the image on the recording surface. The diameter of the aperture is often controlled by a diaphragm mechanism, but some cameras have a fixed-size aperture.
The forerunner to the camera was the camera obscura. The camera obscura is an instrument consisting of a darkened chamber or box, into which light is admitted through a convex lens, forming an image of external objects on a surface of paper or glass, etc., placed at the focus of the lens. The camera obscura was first invented by the Iraqi scientist Ibn al-Haytham (Alhazen) as described in his Book of Optics (1015-1021). Irish scientist Robert Boyle and his assistant Robert Hooke later developed a portable camera obscura in the 1660s.
Early photographic cameras were essentially similar to Zahn’s model, though usually with the addition of sliding boxes for focusing. Before each exposure, a sensitized plate would be inserted in front of the viewing screen to record the image. Jacques Daguerre’s popular daguerreotype process utilized copper plates, while the calotype process invented by William Fox Talbot recorded images on paper.
How to Understand Digital Cameras and Megapixels
The best Summary by David L Whittle
A megapixel is one million pixels. A pixel (or “picture element”) is a small picture cell. Consider a jigsaw puzzle or mosaic where each piece is called a pixel. Each pixel holds a small part of a picture and when they are all put together a picture is formed. For example, one million pixels, or 1 megapixel,creates a picture. Megapixels and resolution is a tricky subject and quite difficult to absorb for the average camera user.
As a rough rule of thumb more megapixels means greater detail or resolution, which means that more cropping or enlarging of your photos is possible. 3-megapixels is a good compromise between quality of picture and camera price. You can print good quality 4×6 images,quite good 5×7s and if a good camera possibly larger prints.
4-5 megapixels and you can begin to think about enlargements of your photos.
6+ megapixels gives great quality pictures and quite big enlargements.
More megapixels means higher prices, more memory usage and the camera takes longer to process shots.
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