Camera

What is Camera?

A Camera is a device takes pictures (images, photographs) of anything you see or you are not able to see. In scientific terms a camera is known as optical device/instrument that captures a visual image. Camera capture images when a specific amount of light enters through a aperture to capture image on an light sensitive surface which can be either photographic film or digital sensor. Various mechanisms are used to control the amount of light to fall on the light sensitive surface. The lenses are used to converge a light entering the camera. As mobile phone cameras mainly uses CMOS active pixel image sensors that reduces the power consumption as compared to CCD(Charged coupled device) type camera.

How does a Camera works?

As many cameras captures light from the visible spectrum, the specialized camera captures other portion of the electromagnetic spectrum Ex. Infrared light. As camera uses a simple design as when light enters an enclosed box through a converging (convex lens) which is controlled by the aperture an image is captured when this light reaches the light sensitive medium. The shutter mechanism is used to controls the length of light time that enters into the camera.

Camera which takes a picture one at a time is called still camera. The Camera that takes picture of a moving object is known as movie camera. When the camera can record a video, it termed as camcorder or video camera. As the majority of cameras are included on phone so it is called as camera phone.

Camera Lenses

Camera lens is defined as the part of camera that guides the light coming from the source to the film or in digital camera, to a integrated circuit that can sense a light. Plastic lenses are the cheapest lens and the lenses which are made from glass material are the better one. The lenses of still camera, video camera, telescope, microscope, mobile camera have the same principle but the architect and the construction are different.

Types of camera lenses

The different types of lenses used by a professional to take different kinds of images are

  1. Telephoto Lens
    2.
    It is the lens that has a longer focal lens as compared to a normal lens. As the angle of view in smaller look closer than they really appear. Longer focal lengths (300 to 1200 mm) are used in sports and nature photography. The telephoto lens which are used for clicking a portraits are 85mm (28°50') and 100 mm (24°).
  2. Wide-Angle lens
    3.
    This type of lenses has a shorter focal length than that of normal lens. As normal lenses have a focal length of 50mm viewing angle between 40° and 50° so as wide-angle lens have an angle of view slight bigger than normal lens that covers an angle of view between 35mm (64°) and 28mm (75°) and extreme views 24mm (84°),20mm (94°), 17mm (104°), 14mm (114°)
  3. Ultra-Wide Angle lens
    4.
    It is a lens which has focal length shorter than of average wide angle lens, that provides an wider angle to take a picture. They come in two variants Fisheye lens with curvilinear barrel distortion, and rectilinear lenses which render image in straight line(i.e., un-curved). Ultra wide-angle lens provides and greater depth of field. The fisheye lens has an angle between 180°-220°.
  4. Zoom Lens
    5.
    The zoom lens is also known as variable focus lens. This camera lens can vary its focal length. The aperture of this kind of lenses have low as compared to other fix focus lenses.

    Digital Zoom

    Digital zoom is a function that all digital camera has. It is a mathematical method which simply enlarges a part of image. It doesn't give a sharp image as compared to optical zoom. When an optical zoom changes the focal length, it also automatically changes its angle of view. While digital zoom simply makes an small part of a image bigger, without changing the angle of view.


Aperture

What is Aperture?

Aperture of photography lens or camera is a hole or opening through which light travels. More exclusively the aperture and focal length of a camera specify the cone angle of a bunch of rays that to a focus in picture plane. When the size of aperture is very small a less amount of light can enter the camera and when the aperture is big, a larger amount of light enters through it.

Aperture Stop is the stop which specifies the ray cone angle and brightness at the image point. Aperture stop is a necessary element in most of optical design. Size of stop is an important factor which affects the depth of field. Smaller stop (i.e., more f no.) creates a longer field depth, which shows the image at a wider angle. With the combination of various shutter speed, the aperture size controls the image sensor or film's angle of exposure to the entering light. The aperture is usually control by a device known as Diaphragm. The diaphragm works similar as an iris of an eye, that's controls the effective diameter of the lens opening.

Different type of aperture of same lens

How is Aperture area is Calculated?

The Area of an Aperture is the amount of light captured by a camera lens in proportional to the area of the aperture; this is represented as 



Were,
N=f/D
f=Focal length
D=Aperture Diameter

What is Focal length?

The focal length of an optical device is a measured by how strongly the system converges or diverges the incoming light on the lens. If the focal length is positive it indicates that the system converges the incoming light, while a negative focal length indicates that a system diverges the incoming light.

What is Field of view?

The Field of view (FOV) is the range of the observable world that is seen at any given moment.

The focal length (f) and Field of View (FOV) of a lens are inversely proportional to each other. If Focal length is increased the field of view decreases and if Field of View is increased Focal length decreases.