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Montclair State University
Introduction to Computer Applications

The Digital effect on Photography



By: John Liddell
For: Professor Robilla
Spring 2006

The word photography can be broken down into two Latin roots: Photo (meaning light) and Graph (meaning writing). It means writing with light, and that is still what it does. Using a series of lenses, mirrors, and time-tested science, it records the light that is reflecting off of surfaces onto photosensitive materials. Today, even after all of the advances of digital technology, that is still what it does. While the materials used for recording light have been switched from film to digital devices, the cameras being used have not changed. In fact, it could be said that the only thing in photography that has changed since its birth is the darkroom. Where once photographers stumbled around in the dark, mixing up chemicals and making countless prints before getting one that was just right, they are now able to sit comfortably at a desk developing and editing their masterpieces on their computer, being able to instantly see the results instead of having to wait for emulsions to develop. As obvious as this concept is to professional photographers, it may not be so well known to the general public who has not had access to the same equipment. In order to illustrate this point more clearly, one must first look at the camera in its three different formats, small, medium, and large.

Small format cameras are cameras that produce a negative size of 35mm or smaller. These are hand-held cameras that are the quickest, easiest, and least expensive to use. (3) They are preferable when you need to have a maximum amount of freedom in movement and when you need to produce a large number of negatives without having to reload the camera with film, as film for the small format camera commonly comes with 36 frames on the roll. The small format camera is relatively small and therefore the accessories, lenses, and flash equipment can be transported from one place to another with relative ease. This type of camera is especially useful for news and action photography where several images must be captured in a short amount of time while under various lighting conditions and changing distances between camera and subject. The primary disadvantage of small-format cameras is that they produce very small negatives. The smaller the negative, the more it must be enlarged during printing, leaving more room for distortions. (1.)

In professional photography, there are two different types of small format cameras, the Twin-Lens Reflex (TLR) camera and the Single Lens Reflex (SLR) camera. The TLR system is commonly used on disposable cameras, also referred to as point-and-shoot cameras, and uses one lens for focusing and viewing and another to direct light to the film plane. The viewing lens is always open wide to make viewing and focusing easy, while the other lens remains at the settings of aperture that have been given it. This is good for many reasons, like the fact that the image is visible on the focusing screen before, during, and after exposure, however, the system has its faults, the main fault resting in the fact that the photographer cannot see the depth of field, making it impossible to control what parts of the image (i.e.: foreground, middle ground, or background) is in focus and what parts are not. This may not be a problem on a disposable camera, where the lenses are in a fixed position, but once the settings on the main lens are changed, the depth of field will change as well. Another disadvantage of this system is that something called a parallax error occurs. Parallax refers to the difference between the image you see and the image you capture through the picture-taking lens. This is because what you are looking at through the viewfinder is not the same as what is shone onto the film plane, as the two lenses are not exactly lined up. This difference is minimal and barely noticeable when taking a large shot, say a landscape, but it is very noticeable when taking a close-up. It takes a lot of practice to learn how to frame a shot on a TRL. (1.)

SLR cameras are much easier to use, and therefore a more popular camera. They have a focusing and viewing system that allows you to see exactly what the camera is seeing. This is done using a simple system that has three basic components: a hinged mirror, a focusing screen, often called a viewfinder, and a five-sided glass prism called a pentaprism. The light is focused through the lens of the camera and shines on the hinged mirror. This mirror is a thin, rectangular piece of glass that is coated on the front with silver. When the mirror is in viewing position, it is positioned at a forty-five degree angle and rests below the viewfinder and in front of the film plane. When light strikes the mirror it shines it up to the pentaprism, which is located inside the camera body directly behind the viewfinder. The light is bounced from sided to side in the pentaprism so that it is not backwards or upside down (as it is bouncing off of a mirror) and then shone onto the viewfinder. Most SLR cameras have what is called an iris diaphragm. (1.) This allows you to change the size of the opening hole, or aperture, of the camera, letting you control the amount of light that passes through the lens. The different settings are indicated by f-numbers: f1.4, f1.8, f2, f2.8, f4, f4.5, f5.6, f8, f11, f16, f22. If the aperture was set on f16, the hole would be much smaller then f2. These aperture settings are usually referred to as stops. The term stopping down means to set the f-stop to a higher number, while opening up means to set the f-stop to a smaller number. While focusing on an SLR, the aperture is open to its widest setting, and it closes to the f-stop it is set for when the shutter button is released. (2.)

To capture an image using an SLR, a series of events must take place between the aperture, the hinged mirror, the viewfinder, and the camera’s shutter, or the part that covers the film, preventing it from being exposed to light until ready to take the picture. This all takes place almost instantaneously as soon as you press the shutter release button. In a fraction of a second after the button is released, the hinged mirror swings up and out of the way of the light path, so that the light can reach the film. The viewfinder is sealed off, preventing any light that is entering through it from hitting the film and distorting the image. The aperture closes to its assigned f-stop, and the shutter opens and stays open for however long the photographer set it to be open for. After the exposure has been made, the shutter closes, the mirror swings down, the aperture opens back up for focusing, and the image is made visible again through the viewfinder. (1.)

Medium format cameras are cameras that produce negatives of one of two popular sizes. One size produces a square negative that is six centimeters by six centimeters, also known as the two and a quarter format (the size of the negative in inches), and the other size produces a rectangular negative that is six centimeters by four and a half centimeters, which is also known as the 645 format. (4.) The film for these types of cameras comes in two different sizes, 120 and 220. Both films are six and a half inches wide, but the 220 is twice the length of the 120 and has its paper backing removed from the middle of the roll to save on space. With the 120 film you can take up to sixteen images in 645 format and twelve in two and a quarter, while with the 220 film you can take thirty-two images in 645 format and twenty-four in two and a quarter format. (5.) Medium format cameras are most commonly used for portraiture, or when relatively large prints are required while still having a relatively free range of motion. (1.) The main draw to medium format is that, due to its larger film size, which is about three to four times the size of 35mm film, you can obtain much higher image resolution. This allows the photographer to make relatively big enlargements while having a smooth gradation without the grain or blur that you would get when enlarging a 35mm negative to the same size. (6.) Further more, because you are using a lager piece of film, you can capture more information from the scene, producing a much more detailed final image. (5.)

With the exception of a few models, the medium format camera does not handle quite the same as small format cameras. A medium format camera cannot be used as quickly as a small format camera, making it extremely difficult to use in things like photojournalism and sports photography. Medium format cameras are usually boxy or bulky due to the larger film size. The camera is set up the same as a small format SLR, but it lacks a pentaprism behind the viewfinder, and therefore the image appears laterally inverted. Using it takes some getting used to, because when you move one way, the image on the screen will shift the opposite way. (5.)

The film on a medium format camera is loaded into a magazine that attaches to the back of the camera. Because the magazine is separated from the camera, some models will allow you to use many rolls of film at once by simply having a couple of magazines loaded at a time. If you need to change the type of film you are using, all you have to do is simply pop the magazine off the back of the camera and put another one, with different film loaded onto it back in its place. This is especially useful because it allows you to change between negative or slide film and black and white or color. (5.)

Besides its many setbacks, the biggest drawbacks of medium format photography are its accessibility and price. Unlike small format, 35mm in particular, where film and photo-finishing services are widely available and cheap, medium format is usually limited to professional photography stores and can be too expensive for some. (6.)

Large format cameras are cameras that produce negatives of 4x5 or larger. It is the standard format for photographing architecture and interiors. (3.) Large format cameras are used when you need maximum detail in the negative. This is required when subjects are photographed to exact scale or when very large prints are required. (1.) The large format camera, also known as the viewfinder camera, is known for it’s superb quality and the total control it gives you for capturing the image. The larger negative allows the photographer to make sharper images with more detail. (7.) Images made using large format cameras are better in tonality and virtually grain free. Because of the large negative, you can make contact prints, where the negative is laid straight on the paper being exposed. Contact printing produces an image whose delicacy cannot be matched by any enlargement, and allows a number of ‘alternative’ processes. (8.) The large format camera, while producing amazing enlargements and contact prints, is not without its faults. Viewfinder cameras are much bulkier and slower to operate then small format or medium format cameras. They take sheet film, which have to be loaded into the camera one at a time, making the time between shots very long, as the camera is invariably moved after each time you load it and the shot has to be set up all over again. (7.)

The Large format camera consists of three basic components. Interchangeable lenses, a flexible bellows, and a ground glass viewing screen. The lenses are mounted to a sheet of metal that slides into the front of the camera. Connected to the front of the camera is the flexible bellows. The fact that they are flexible allows the photographer to use a range of focal lengths and focusing distances. They allow the photographer to tilt and slide the lens plane and the film plane, allowing for many controls that include lateral and angular adjustments. The ground glass viewing plane is in the back and sits behind the slot through which you slide the film into the camera. It is usually marked off with a grid that allows the photographer to better set up the image, as lines and angles are easily distorted. (8.) The image shone onto the ground glass viewing plane is usually very faint, and the photographer must use a dark cloth, a piece of black fabric that covers the camera body and the photographer’s head, and a loupe, a magnification device, to view and better focus it. These three parts are usually mounted on a monorail that allows everything to slide forwards and backwards as the photographer sees fit. (7.)

The large format camera was the earliest type of camera to be used, and to the present day it remains relatively unchanged. It is an adaptation of a device called The Camera Lucida, which dates back to the time of Leonardo DaVinci. The Camera Lucida was a tool used by artists to make a more precise image. Just like today’s viewfinder camera, lenses were used to focus an image onto ground glass, where the artist would trace over it. (9.) This very clearly illustrates that photography has gone through little change over the years, even since the time of the renaissance, and still will not change with the invention of the digital camera, as the digital camera still employs the same technology as film cameras. The only thing that has changed is the way that light is recorded.

In small format photography, film is now replaced by CCDs, or Charge Coupled Devices, which capture the light data and transfers it to a memory card. A CCD is an image sensor that consists of an integrated circuit that contains an array of linked, or coupled, capacitors that are sensitive to light. There are several different types of CCDs. The type used in digital small format cameras are referred to as two-dimensional array, which, as opposed to one-dimensional array, which capture only a slice of the image at a time, are able to capture the whole image at once, or at least a rectangular portion of it. When light is shone onto the CCDs, each capacitor accumulates an electric charge that is proportional to the light intensity at that location. Once the CCD has been exposed to light, a control circuit causes each capacitor to transfer its contents to its neighbor. The last capacitor in the array dumps its charge into an amplifier, which then converts the charge into voltage. Te process is repeated and the control circuit converts the entire contents of the array of capacitors into varying voltages, which it then samples, digitizes, and stores in memory. Stored images can then be transferred to a storage device, a display screen, or printed. (10.)

In order for the two-dimensional array CCDs to capture color, a Bayer mask must be placed over the CCDs. This breaks CCDs down into squares of four pixels each. Each square of four pixels has one filtered red, one blue, and two green (since the human eye is more sensitive green then either blue or red). The result of this is that luminance, or color density, information is collected at every pixel. (10.)

New technology is being developed so that color captured on CCDs will look even better. The new devices will be three-CCD devices and will make use of a dichroic beam splitter prism which will split the image into its red, green, and blue components. Each of the three CCDs is set up to respond to a particular color. This Technology is already being put to use in some professional and semi-professional digital video camcorders. (10.)

As in traditional film photography, the same technology has been applied to digital medium format photography as small format photography. Both of these systems employ the two-dimensional array CCD system. In the past, however, digital technology for medium format photography was a bit clumsy. In order to shoot digitally with the medium format camera, the photographer used what is called a digital back. This was rather heavy and bulky and attached to the body of the camera where the film magazine would attach. They were not very portable, as the back did not have any storage in it and you had to be connected to a computer via fire wire in order to shoot and save your work. The medium format camera company Hasselblad is changing this.

Hasselblad has recently released a fully integrated digital camera called the H2D. The H2D provides optimum portability and image storage. Photographers will now have the option of storing the images on a Compact Flash card while shooting, or they may still use the fire wire if they wish. (11.)

Digital large format photography makes use of the one-dimensional array CCD system. The information for the image is collected by three individually filtered rows of pixels. This is called a tri-linear CCD. This system requires images to be slowly scanned line by line rather then taking the image all at once. This causes a problem for some photographers because it limits the type of lighting you can use. Because the scan back works so slowly, using a flash or a strobe light is out of the question. One is forced to use an alternative light source, and not all others are as reliable as a flash. However, the wait and the inconvenience with lighting is well worth it, as the resulting product is a large, high-resolution file with extraordinary detail, allowing the photographer to have superb control of color and tones. The scan-back easily slides into the film slot of a large format camera and collects the same light data that would be hitting the film. Perhaps the only inconvenience with the system is that, like in the early stages of digital medium format, you must be connected to your computer in order to take a shot. (13.)

Where once photographers needed expensive enlargers and special chemicals as well as otherwise specialized equipment to print and edit their photos, they now only need a modern computer with a reasonable processor and plenty of memory and a decent enough printer with photo paper. Film and slides that once took up valuable space are no longer needed, as images can now be stored on CDs and DVDs. Where negatives and slides eventually deteriorate, images can now be preserved indefinitely by continually copying the disk they are stored on. With programs like Adobe Photoshop and Photo-paint, images are very easily manipulated to produce an infinite amount of possibilities, even mimicking traditional darkroom techniques. (2.)

Even with the birth of digital photography, the field has seen little change. The time-tested camera is still what it always was. It is the way that the light is recorded and the tools used to print it out that have changed. Some people may argue that quality may be compromised when shooting digitally, but the possibilities of digital are endless and surely make up for any quality that may or may not have been lost. If nothing else, the digital format has made photography much easier and much less messy.


References



1. http://www.tpub.com/content/photography/14209/index.htm
2. http://www.theimageplane.net/photbac.htm
3. http://www.homeresourceguide.com/about-photography.html
4. http://home.hawaii.rr.com/asm/medium.html
5. http://www.nelsontan.com/articles/mfphoto.html
6. http://en.wikipedia.org/wiki/Medium_format
7. http://www.jafaphotography.com/intrlg.htm
8.
http://www.largeformatphotography.info/why.html
9. http://www.skgrimes.com/lgformat/
10. http://en.wikipedia.org/wiki/Charge-coupled-device
11. http://blog.fotolia.com/us/product/hardware/hasselblad-digital.html
12. http://www.betterlight.com/products4x5.asp