your life through the lens

FIVE BASIC FEATURES OF CAMERA
LENS - The lens is the eye of the camera. Its function is to bring light from the subject into focus on the film. A camera can have a single lens or a complex set of lenses. Together with the shutter, the lens controls the amount of light that enters the camera.
FILMS - Certain characteristics help people determine which film will work best in a particular situation. Films may vary in their sensitivity to different kinds of light and in their ability to record fine details or quickly moving subjects.
VIEWFINDER - A viewfinder enables photographers to frame their subject the way they would like it to appear in the finished photograph. Some viewfinders consist of a simple window on top of the camera that only approximates the view through the lens. A more complex and more accurate viewfinding system is the single-lens-reflex system, described above.
SHUTTER - The shutter, a spring-activated mechanical device, keeps light from entering the camera except during the interval of exposure. Most modern cameras have focal-plane or leaf shutters. The focal-plane shutter consists of a black shade with a variable-size slit across its width. When released, the shade moves quickly across the film, exposing it progressively as the slit moves. In the leaf shutter, at the moment of exposure, a cluster of meshed blades springs apart to uncover the full lens aperture and then springs shut.
APERTURE - The lens diaphragm controls the size of the aperture, or lens opening, and thus the amount of light that passes through the lens. It operates in conjunction with the shutter. The aperture size is measured by numerical settings called f-stops. On a traditional, manually controlled camera the f-stops are inscribed on an adjustable ring that fits around the lens. Typical f-stops are f/2, f/2.8, f/4, f/5.6, f/8, f/11, and f/16. The setting f/2 represents a large aperture, f/16 a small aperture. With simple automatic-exposure cameras, a computer sets the aperture size; thus the aperture ring has disappeared from many of today's lenses.
Lenses come with a rating for their maximum aperture, indicating how much light can reach the film when the lens diaphragm is wide open. With single-lens-reflex cameras, the maximum aperture also influences how bright the image appears in the viewfinder. Within lens types, a lens with a large maximum aperture will have a larger diameter and weigh more than a lens with a smaller aperture. A telephoto lens requires a larger lens diameter and greater length to let in the same amount of light as a normal or wide-angle lens. Like telephoto lenses, zoom lenses are also physically large. To reduce their bulkiness and complexity, many manufacturers now design zoom lenses with a variable maximum aperture: The size of the aperture changes as the focal length of the lens goes from wide-angle to telephoto settings.

TYPES OF CAMERAS

Point and Shoot Camera

The most popular camera type today is the point-and-shoot camera. It has a number of automatic features that make it practically foolproof to operate while producing pictures of high quality. Point-and-shoot cameras feature battery-operated electronic systems that may include automatic controls for exposure, focusing, flash, film winding, and film rewinding. They are available with a fixed single-focal-length lens or a zoom lens; the lenses cannot be removed from the body.

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. While there are still some P&S film cameras, such as the disposable or one time use cameras, most P&S today are digital.

Features
• Metering systems, which calculate the amount of light entering the camera
• Variable shutter speed
• Variable aperture
• Zoom lenses
• Automatic focus
• Preset controls for various photographic situations such as:
o landscapes
o nighttime
o people
o close-up or macro

The biggest drawback to P&S cameras is that many do not have a through the lens (TTL) viewfinder. This means that what you see through your viewfinder may not be what you capture on film or digital media. P&S cameras are usually small and fit into a pocket or purse. They are best used for casual picture taking where capturing the memory is more important than creating a marketable image.



Single-Lens Reflex Cameras-One of the most popular designs available today, the single-lens reflex (SLR) both views and photographs through one lens. Light passing through the lens is reflected by a mirror and brought to focus on a ground glass. The mirror causes a reversal of the image seen on the ground glass, but the addition of a pentaprism mounted over the ground glass allows the camera to be used at eye level, with the image seen upright and in proper left/right orientation. An instant before the exposure is made, the mirror swings upward, and the shutter is activated. A single control cocks the shutter for the next exposure, advances the film, and returns the mirror to focusing position.



Instant Cameras-An instant camera will produce a finished print in from 20 seconds to about 4 minutes. The film, after exposure, is passed between two stainless steel rollers inside the camera. These rupture a chemical pod on the film and spread developing agent evenly over the film's surface. In the original Polaroid system it was necessary for the user to peel the finished print from the base material. Professional Polaroid films, both color and black and white, are still developed in this manner. With the Polaroid SX-70 (1972), however, the developing picture is ejected from the camera, and the film reaches its final development in full daylight. The process is completed in about 4 minutes. Later instant cameras use a new focusing system employing an ultra-high-frequency sound emitter. An electronic circuit in the camera measures the time required for the sound to be reflected back from the object being photographed. This time measurement is converted into a measurement of distance, and an electrical mechanism coupled to the focusing circuit sets the lens for the proper exposure.In 1993, Polaroid introduced a single-lens reflex model that does not eject shots like other instant cameras but instead transports the developed picture to a viewing area and container on the camera back.
Disposable Cameras-A disposable camera is a cardboard box containing a roll of film and a lens along with a simple viewfinder, a button for shooting, and a film advance mechanism. Like the earliest box cameras, the lens is fixed in focus--that is, its aperture is small enough so that anything more than about four feet away will photograph in focus. After the user has shot the full roll of film, the entire camera is returned to a processing lab, the film is developed and printed, and the box and its fittings returned to the camera maker who will use it to make new cameras.

VIEWING SYSTEMS

SINGLE LENS REFLEX
• Single Lens — The camera uses one lens for both taking and viewing. In other words you look through the same lens as the camera uses to expose the film or sensor (as opposed to twin-lens reflex cameras).


TWIN LENS REFLEX
• Twin Lens — The camera uses two lenses, one for viewing and for taking.


FOCUSING SYSTEMS

RANGEFINDER- Rangefinder cameras were the first cameras to have an optical viewfinder—that is, a separate, window-like lens through which the photographer sees and frames the subject. The viewfinder is paired with an adjacent window called a rangefinder. To focus the camera, the photographer adjusts a ring or collar until the two views appear as one, at which point the camera has set the focus to precisely match the distance of the subject. Since the viewfinder window does not show the scene through the lens, but only one that closely approximates it, rangefinder cameras can be inaccurate for framing close-up shots.
Rangefinder cameras were once very popular with amateur photographers, but today’s point-and-shoot cameras have largely replaced them. Nevertheless, the modern rangefinder camera works well under certain circumstances, and some professionals still use it. Rangefinders are available in two formats, for use with either 35-millimeter film or the larger format 6-centimeter film. Unlike point-and-shoot cameras, modern rangefinders feature lenses that can be removed from the camera body so that photographers can choose a lens specifically suited to the subject.


AUTOFOCUS- Autofocus cameras use electronics and a small computer processor to automatically sample the distance between camera and subject and from this determine the exact plane of focus. The computer then signals a small mechanism that turns the lens barrel to this point.
There are two widely used methods for determining the focus automatically, called active and passive. An active autofocus system, used in most point-and-shoot cameras, emits either an infrared light beam or high-energy (ultrasonic) sound waves. When the light or sound waves bounce off the subject and return to the camera, they give an accurate reading of the distance to that subject. Passive systems, used in more sophisticated cameras, automatically adjust the focus of the lens until sensors detect that maximum contrast has been reached inside a rectangular target at the center of the focusing screen. The point of maximum contrast corresponds to the point of greatest sharpness.