Reflection On The Lens From Unwanted Light example essay topic

The most important thing to photography is light. The camera is a precise instrument for capturing light. The word camera in Latin means room. The name camera comes from the first invention towards capturing the world on film, the camera obscura or dark room. This invention came about in the 14th century and was used by such artists as Da Vinci and Michelangelo to more accurately draw their subjects onto paper.

The invention of this box, made way for more advancements in cameras and photography. There are five essential items in cameras that make photography possible. They are exposure, refraction, plane of focus, angle of view and aperture. Exposure is the amount of time a camera lets film be exposed to light. Refraction is the bending of light through the lens (es) of a camera.

Plane of focus is the area where light reforms an image in the film. Angle of view is the angle created on a lens when you take the two most outer points you can see through a lens and diverge them to the exact center of the lens. The angle created will be the angle at which the camera can take pictures at. Aperture is the amount of light a lens allows into the camera. The camera obscura, as mentioned previously, was a large box or even a whole room. There would be a small hole in one side, where light could enter.

It would be pitch black inside the box except for where the light shined though the hole. An artist would sit inside the box while the subject would sit between the hole and the light source. As light would travel through the hole, the hole would act as a lens. The artist could then trace the subject with greater accuracy than if done freehand. This also helped perspective come more easily to the artist. There are two individuals that made it possible for photography and cameras to advance forward as much as they have today.

One was Joseph Nicephore Niepce. Niepce is credited with making the first successful photograph in 1826. Niepce was experiment in with the new form of print making called lithography. While doing this, he discovered that a material called bitumen reacted to light, and he could make exact duplicates of lithographs.

Using this light sensitive material called bitumen, he coated a plate of either glass of pewter with this material and placed it in the back of a camera obscura and exposed it to light. He now had a template for the printing of duplicate lithographs. Niepce was anxious to share his findings with someone else. That someone else was a theatrical designer and owner of a theater in Paris named, Louis Jacques Mande Daguerre in 1829. He was the other individual responsible for the camera and photography.

Daguerre had also been experimenting with the camera obscura to help produce images, but had little to no luck, until Daguerre and Niepce got together. Daguerre's most important discovery came only two years after Niepce's death in 1835. Daguerre's discovery was that of another light sensitive material more sensitive than bitumen. This was silver iodine. The problem with this was that the compound darkened over a period of time.

This was eventually solved by washing the plate coated in this compound with warm water and table salt. On January 7th, 1839, this process in developing pictures on plates became known to the public as the daguerreotype through the French Academy of Sciences. Daguerre was given a lifetime pension by the French Government in exchange of the rights to the invention and full public disclosure of the process. The Daguerreotype was to be a gift to the world, from France with love. One last invention came forth from England by a man named Henry Fox Talbot. He used a solution called silver chloride to make pictures.

This was different from the daguerreotype in that it used a positive-negative process similar to the process used today. This was perfected in the 1840's. Talbot used paper at first for the negative, but later in 1850, changed over to glass. This process was called a collodion or wet plate. Called this, because a photographer would have to first coat a plate with the silver chloride, then place it in the camera obscura, later replaced by a special camera with a lens and a bellow, before he could take the picture. Silver chloride was replaced by silver bromide suspended in a gelatin to create a dry plate that could be prepared before hand rather than just before the photograph was to be taken.

In the 1880's, more sensitive solutions led to an up rise for a more regulated control of inlet of light. This led to the invention of the shutter. At first, they were just spring loaded blinds dropped in front on the lens. Later the innovation of a set of blades as a shutter came to be. George Eastman, in 1878, came up with a system of flexible negatives. A long strip of paper could replace the glass plates.

In 1889, he improved this by using a plastic called celluloid. This was highly effective as a film, but also highly inflammable. In 1888, Eastman invented a new type of shutter, the cylindrical shutter. It consisted of a cylinder and a string that the photographer pulled to release it.

The next thing invented by Eastman was the box camera. I had a rigid box, a fixed lens, a viewfinder, and an improved spring shutter with one or two speed settings, a set aperture and a set focus. This meant that in order to focus the image, the subject would have to stand approximately 2 meters away. Not highly effective, but an incredible leap over the others. The next company after Kodak to innovate a camera was the Leitz Company in Germany. The Leica, in 1925, had two especially important features.

One, it was the first camera to use 35 mm film. Before that, 35 mm was reserved for movie film. The other was a focal plane shutter. This was located behind the lens and allowed a lens change while a roll of film was still in the camera. After Kodak and Leitz, many other camera makers came into the picture.

There were many types of cameras to come after the box and the Leica. There was the view camera, the range finder, the point-and-shoot, and of course, the Single Lens Reflex or SLR. The view camera had several new features over that of its predecessors. Despite its awkward weight and size, it gave superior focus, aperture and framing. It used large format films, unlike the Leica, which used 35 mm.

This gave better contrast and sharpness. The view had an extremely adjustable body configuration. It was composed of two individual, moveable elements. The front element held the lens and shutter, while the rear held a round glass panel. The space in between had an expandable leather bellows. The way one would shoot this camera was to first focus and frame the shot.

Then one would place the film holder into the rear element in front of the glass plate. Then, click, the picture is taken. This camera was great for studio, landscape and architectural shot, but utterly useless in action situations. You could shift the rear and front elements separately to ensure maximum focus and precision perspective. The range finder was the first to incorporate an optical viewfinder and a range finder. To focus this camera, you would adjust the focus ring until the image in both the range finder and the viewfinder became one.

This was a great camera for shots at a distance, but there was some aberration in close ups. The single lens reflex is the most accurate in exposure, framing focus and aperture. It uses a system of interchangeable lenses and has the most sophisticated moving parts to make it not only the best for taking pictures, but one of the most tricky to uses, seeing that there is so mush to master. The main features that make this so versatile are it's shutter, optional auto focusing, interchangeable lenses, aperture systems, light metering systems and flash capabilities. The shutters are spring activated and keep the light from exposing the film. There are two kinds used in SLRs, the focal plane, like that used in the original Leica, and the leaf system.

The Focal plane used in the SLR is different than that of the Leica, though, based on the same idea. It blocks the light from exposing the film allowing lenses to be changed in the middle of a film roll. This also allows the SLR to use through-the-lens framing. This is done by a mirror in front of the shutter at such an angle it reflects it straight up into a pentaprism, or a five sided prism. This is specially made for each camera so that the light is reflected inside the prism twice in total internal reflection. The light enters through a perpendicular plane on the prism, then it is reflected at the critical angle of an angled plane onto another angled plane where it too reflects the light.

Then it travels through another perpendicular plane. It then travels through the eye piece or viewfinder. The shutter is controlled by a microprocessor in most SLRs, but can also be manual in many older ones. The mirror will flip up and an instant later the shutter will expose the film for the allotted amount of time. The way the focal plane shutter works is it uses a slit to uniformly expose each piece of film for the given time, or for long exposures just opens up fully.

The leaf shutter serves the same purpose as the focal plane, but it has a system of over lapping leaves that open and expose the film all at once every time, slow of fast shutter speeds. The next and most important things are the lenses. The lens is the eye of the camera just as the film is the retina. It brings light from the subject to the film. The lens can be a single lens of a series of lenses all to serve one purpose. The camera obscura was the first camera to be fitted with a lens.

Its purpose was to sharpen the image on the paper inside the camera. It used a convex or converging lens. In the 19th century, the growing photography industry had a growing demand for specialized lenses specifically for the camera. The development came in two fronts. The first was an invention of new types of glass and the second was a development to combine several pieces of glass to create better lenses. Today's modern lenses are actually made up of several lens elements and assembled in a lens barrel with an aperture ring and focusing ring.

The focusing ring sharpens or blurs the image by changing the distance between some of the lens elements. The aperture ring controls the amount of light entering the camera. Different lenses have different focal lengths to perform different photographic tasks. The focal length is the distance from the central point in the lens to the plane of focus on the film.

Lenses are categorized by their focal lengths and maximum aperture. Larger focal lengths produce larger images and greater aperture means more light can enter the lens. Lengths are determined by measuring the distance from the central point to the plane of focus, when the lens is focused at a distant point on the horizon called infinity. Short length lenses are called wide-angle lenses, because they produce wider angles of view. While shorter lengths are called telephoto and produce a smaller angle of view.

Also wide angle lenses produce distant objects while telephoto lenses produce closer objects. Another of the lenses, and one of the most popular, is the zoom lens. These lenses offer a wide variety of focal lengths. A user can change the length just by pushing a button on more automated models or turning a ring on older models. True-zooms stay in focus at any focal length, or need minimal adjustment.

Vari focal zooms on the other hand must be adjusted every time a new length is selected. This is very annoying unless your camera has an auto focus feature. There are many special tasks that must be performed in photography. There are a variety of lenses to satisfy each one of these tasks. On of the most common specialized tasks is close range photography. A lens called a macro lens will extend the range of focus to a mere few inches in front of the lens.

On there own, macros produce an image size of +. An extension ring can correct this and increased image size to 100%. Another task is photomicrography, an extension on the macro principal. It uses a special connecting lens to allow the camera to be attached to a microscope. There are so many types of lenses for so many tasks. It would be nearly impossible to name them all and their purpose.

Aperture is one of the most essential parts of photography. It allows light in or restricts it. It helps with exposure and in conjunction with focal length, creates what is called depth of field. The lens diaphragm controls the aperture with overlapping leaves. Each setting is given a numerical representation. These are called f-stops.

The formula to get the f-stops is: Where Lf is the focal length and Da is the aperture diameter. The f-stops are inscribed on the aperture ring. Some typical f-stops are: f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16. F/2 represents a large aperture.

F/16 represents a small aperture. All lenses come rated with a maximum aperture, that is the maximum allowed amount of light entering the lens. The larger the maximum aperture the larger the lens must be. As mentioned before, aperture is a major ingredient in depth of field. Depth of field is simply the depth at which objects focus. A large aperture produces a small depth of field.

Long focal lengths do the same. For the maximum depth of field, that is everything seems to be in focus, a low aperture on a lens with a generally lower focal length at a great distance will be the best for producing this. Sometimes, a photographer will get what is known as a lens flare. What that is a reflection on the lens from unwanted light. Lens companies combat this with a special coating that absorbs light rather that reflecting it. This is similar to the coating on the stealth fighter.

Lens coatings also increase contrast. Another way to prevent this unwanted light is with a lens hood. This simply blocks the light from the sides to prevent the light rays from striking the glass at its critical angle causing flare. Light metering is an essential advancement in photographic technology. Developed in the 1930's, light meters were hand held and could be very bulky.

They later incorporated them into the cameras in the 1960's. This advancement helped photographers frame the shot and correct the exposure in the same step. There are four kinds of internal meters. Match needle, aperture priority, shutter priority and digital readout. Match needle systems require you to match two needles to correctly expose the film.

The aperture priority automatic system eliminates one variable, the aperture. It automatically adjusts the aperture setting and all you have to do is set the correct shutter speed. The shutter priority automatic system allows the camera to take control of the shutter speed while you adjust the shot to the correct aperture. The digital readout is on most fully automated point and shoot SLRs, it adjusts everything for you or allows you to see the correct settings for both aperture and shutter speed and manually adjust them both. All metering systems share one thing, they respond to the world as if they were one uniform shade of gray. The shade of gray is 18% gray, named for its reflection ratio.

It represents the average amount of light reflected by an average outdoor object. This is a reflected light meter. The other type of meter is an incident light meter. It measures the amount of light falling on the scene.

Most meters are averaging meters because they average all the light in the shot. Meters that measure the amount of light in a narrow angle are called spot meters. Though Averaging meters are somewhat less accurate, spot meters are often very hard to use and you must be able to interpret their readings. With recent advances in light metering and electronics getting smaller and smaller by the day, cameras are now being equipped with automatic systems such as autofocus and autoaperture. Autofocus is based on the principal of reflection.

There are two auto focusing systems, active and passive. Active systems use reflected infrared light or ultrasonic sound to judge the distance between the object and the camera. This is usually accurate, but not always. If there is an object in front of the one you are trying to focus in on, it will focus in on that abject and blur the rest of the scene. Passive systems correct the problems with active systems, but come with their own.

Passive systems use special sensors behind the lens to correctly adjust the camera to the maximum contrast in a rectangular target. If you are photographing a large sail on a ship, for instance, the autofocus will not work. Wit advancements in internal light metering systems, cameras have a system for measuring the amount of light on the scene and can adjust automatically the correct aperture using a microprocessor. The same system can be used to adjust the shutter speed too. Some cameras have both systems. The absence of adequate daylight in any scenario calls for the use of artificial lighting.

The most common sources of artificial light are tungsten lamps, quartz lamps, and the most widely used and most useful, the electronic flash. The electronic flash was invented by Harold Eugene Ed garton. He developed the electric strobe light that you would see at any club or concert, or stroboscope. With this invention, he photographed a bullet in mid flight at a flash rate of 1/500,000 of a second. Today's electronic flashes fire at a rate of 1/1000 of a second to 1/5000 of a second. Though, rates of 1/100,000 of a second are now more readily available.

Flashes vary in size, from small battery operated ones that sit on top of the camera, to very large expensive studio flashes that are required to be plugged in. The small units are sufficient enough to flood an already lit scene to get rid of harsh shadows, light close ups and portraits and other such snap shots. Studio flashes are much brighter and can flood the scene with immense amount of light. Their flash rate can be varied and are great for large areas. There are more expensive camera top flashes that can be angled, fire faster and flood a larger amount of light on to the scene which makes it a portable studio flash for out doors and action. Electronic flashes are usually quarts glass tubes filled with an inert gas- usually xenon.

When a jolt of electricity is applied to the electrodes within the tube, a bright flash occurs. This is much more efficient than the old one time use flash bulbs filled with oxygen and fine magnesium alloy wires. One other important object to the advanced SLR user is a filter. Filters are small pieces that are made of either gelatin or glass. They screw onto the front of the lens. There are tons of different filters to accomplish different tasks.

Filters can correct lighting, change the contrast or brightness, minimize haze or create several special effects. In black and white photography, different colored filters block out one color while allowing its contrasting color to pass. This can give different effects with different colors. A red filter for instance, blocks a large amount of blue.

If used in landscape photography, it will make the sky appear darker giving greater contrast between the clouds and the sky. A medium-yellow filter is most commonly used in outdoor photography because it renders the sky much the same way as the human eye does. A conversion filter is used when the color balance of the light being used is dramatically different then that of the film being used. If tungsten film was to be used outside in sunlight, a bluish color would permeate over the picture. A conversion filter, series 85, will correct this. Daylight film, which is color adjusted for sunlight at noon, will create an amber cast on film when exposed indoors to incandescent light or photofloods.

A series 80 conversion filter will correct this. Color-compensating (CC) filters help balance film to work correctly with fluorescent lighting. Photographers can also use these CC filters to make small color adjustments on the film or when printing in a dark room. Ultraviolet (UV) filters are the most common filters to be used. They filter virtually all UV light, which is invisible to humans, but can register as blue on film. Another reason many people use this filter, Is it doesn t alter the picture any other way, so it serves as a clear protective lens cap for the camera.

Another great filter to have is a polarizing filter. This filter works on the premise that light can be polarized, that is made to only come in at one direction. This filter has numerous parallel slits. When light is emanating from a source, it vibrates in all directions. If this light strikes any non-metallic surface, such as glass, it is reflected in a polarized state. In order to get rid of this reflection, such as reflection on glass in a store front window, simply screw in this filter, and turn it until the reflection is gone.

There are so many new cameras coming out today from so many companies it's hard to keep track. The most common is the point and shoot camera (PAS). The point and shoot camera incorporates many of the advanced features of the SLR into a compact design that is light and very easy to use. Most of today's PAS have autoaperture, autofocus and auto-shutter speed.

Other features that have been added to PAS cameras are such things as red-eye-reduction, autoadvanceing, auto rewind and light meters to automatically shut off the flash. The effect of the red centers in the eyes of the subject in photographs is commonly called red-eye for obvious reasons. This happens because the iris of the eye is open too much allowing in too much light. This causes a red reflection off the retina. To compensate, cameras have a feature that floods the eye with a bright light before snapping the shot causing the iris to close enough to eliminate the red-eye effects. Though there is still no comparison to the SLR with all its adjustable features to make it more versatile than the PAS, which has virtually no adjustable features.

More advancement in today's technology has brought forth two new technologies, the Advanced Photo System (APS) and digital photography. The APS film is greatly different form conventional 35 mm film. For one thing, it is smaller than the regular 35 mm film. It also records all the information onto a magnetic film, very much like the floppy disks you use in your computer. There is no leader to be wound on a take-up spool and according to its creator, the Eastman-Kodak Co., it produces a higher percentage of well exposed shots with the same high detail and sharpness of the larger, conventional 35 mm format. Automated machines do all the developing work, so there is no human error.

There is also now talk of a machine for the computer to develop and scan all the pictures straight onto the computer, and now with improving graphics for printers, people can create a home photo lab with a decent investment. With a good graphics editor, you can also create artsy type photographs with out spending a fortune on lenses and filters. Digital photography took the world by storm in the 1990's and was starting to quickly replace the conventional camera in the field of photojournalism and advertising. Digital cameras are now readily available to the general public for a couple of hundred dollars. There are more sophisticated types of digital cameras the professional photographers use. These work just like SLR's, but record the picture in a set of ones and zeros via a scanner instead of using 35 mm film.

All digital cameras use the binary system to record their pictures. Amateur photographers use digital cameras in the same way as a PAS camera. The more sophisticated the camera, the higher the resolution, that is the amount of pixels there are in the shot, is. A pixel is a digital dot of color created by a series of ones and zeros. Also the higher the resolution, the more money it is. Cameras have been with us since as early as the Civil war and have flourished ever since.

As the technology expands so will the capability of how well a picture will become. There has been more of a jump to the digital side lately, but there still is no comparison, yet, to the quality and freedom of conventional cameras. Most people have been taking pictures since they were kids and cameras and photograph has been a major part of American culture because of it. Not only is it a part of American culture, it is part of world culture. For this, photography will live on for ever.

Who knows what the next step forward is. It could be anything, because in this day and age anything is possible.