In order to understand the process of digital photography, first we must understand how the camera operates. Similar to traditional film cameras, digital photography uses the principles of camera obscura in order to capture an image. As mentioned previously, camera obscura is a process in which natural light is harnessed through an optical phenomenon which produces a mirrored upside down image. It occurs when light passes through a small hole into a completely dark space.
Cameras essentially do the same thing – they are basically handheld versions of camera obscura. They allow light to pass through a lens, which is then exposed, to film. Lenses are usually composed of 1 to 12 elements. The elements vary depending on the make model of the lens as well as what type of focal length the lens is.
Typically, there are three basic types of lenses – normal, wide angle, and telephoto. A normal lens most closely represents the human eye. It’s usually at a range of 50 mm for full frame cameras. For APS-C (Advanced Photo System) cropped cameras, a 35mm will be the closest to a normal lens. Wide angle lenses usually range from 10mm-35mm. Wide-angle lenses have the ability to exaggerate the relative size of subjects as well as the background. Usually, these lenses are used for capturing landscapes. Telephoto lenses are a specific type of long-focus lens. Usually the range of this lens is from 85mm to 135mm. These lenses are used to capture subjects from far away. The construction of this lens also produces very interesting effects. It essentially compresses the subject and the background to make it appear as if things are closer together. Also, this lens usually produces a short focal range meaning that the background of the subject remains out of focus.
When referring to focal length of a lens, this is the unit of measurement of how strongly the lens converges or diverges light. It’s quite an expansive process that doesn’t need too much explanation. In general, focal length is the distance from the lens to the film when focused on a subject.
In order to take a photograph, there is a particular exposure process that depends on various calculations of available light. There are three very important settings every photographer must know before taking a photograph: aperture, ISO, and shutter speed.
Aperture (or F-Stop) measures how big the opening (diaphragm) of a camera is in order to let light pass through (Cambridge). When compared to the human eye, the aperture most closely resembles your pupils. Typically, pupils have the ability to dilate depending on lighting conditions. When it’s dark your pupil enlarges to allow more light to enter your eye. When it’s bright your pupils shrink to limit the amount of light. The aperture in a camera does the same thing. It uses a series of overlapping metal wings, called a diaphragm, that when opened or closed controls the amount of light that is allowed to pass through a lens. In photographer slang, when someone says they are “stopping down” or “opening up” they are referring to the increasing or decreasing of an F-Stop value. The larger the number, the smaller the F-Stop. For example, f/22 uses less light than f/2.8. f/22 has a smaller diameter than f/2.8, even though the value is larger.
Interesting effects take place when you control the f-stop values. When you have a large f-stop (ex. f/2.0) then you are allowing more light to enter the camera. However, you are also creating a shallow depth of field. This means that the background of the subject will become more out of focus. When you have a small f-stop (ex. f/22) then you are limiting the amount of light to enter the camera. In turn, this allows you to have a large depth of field – meaning that the subject and the background are both in focus.
ISO (or ASA) determines how sensitive the camera is to incoming light (Cambridge). In traditional film cameras, the film stock has a predetermined ISO. Typically, the lower the ISO, the higher the quality of the photograph. This means there is less image “noise.” Noise refers to the graininess of the image. They are tiny artifacts that affect the quality of the photograph. The higher the ISO, the more light sensitive the film is. This means that in low light situations you would use a higher ISO to capture an image. Unfortunately, the drawback of a higher ISO is more image noise/grain. Luckily, in today’s digital cameras, there are many options for ISO settings. Some cameras can reach up to 12800 ISO internally. It’s like having multiple film stocks at the same time. It saves time and money.
Shutter speed determines when the camera’s sensor will be open or closed to incoming light from the lens (Cambridge). In a camera, there is a mirror that opens or closes. This allows the light to expose the film (or in digital cameras, the sensor). Shutter speeds controls the exposure time. Typically, the smaller the shutter speed the less time the film is exposed to light. When using shutter speed, creative opportunities arise. Objects in motion can be difficult to capture. That’s why you control the shutter speed. For low light shots, if you expose the camera longer then you can capture images like fireworks or lightning. Many photographers use slow shutter speeds for moving water. This gives it a creamy and almost heavenly look. The water isn’t as sharp, allowing it to flow more organically.
When altering these three settings in tandem with what lens you choose, interesting photographic results can occur. As a photographer, you officially have control over your camera. Many digital cameras have built in settings that allow you to adjust certain aspects that help produce better images. Most professional photographers shoot in manual mode for complete camera control. Picture styles and settings also give you creative control over how your images are captured. Many professionals prefer to shoot in neutral modes and in RAW format for maximum quality. In camera, the results are less than satisfactory – on the LCD screen the images look dull and gray. However, shooting this way allows all possible digital information to be transcoded without any loss of information in the shadows, highlights, or tones of an image. This provides maximum control over your image when editing.
Unlike traditional film cameras, which rely entirely on chemical and mechanical processes, digital cameras use a built in computer that helps record images electronically. Instead of using traditional film stock, digital cameras have a built in sensor that digitally records image data. “Unlike chemical film cameras, digital cameras have no resolution limits- they can take pictures as large as their CCDs and storage cards allow (Johnson 2001)”. This little device is called a charged couple device (CCD) or a complementary mental oxide semiconductor (CMOS). Both devices record the amount of light that enters the camera through the lens. It then converts that information into digital data that can later be stored or manipulated.
Computer space is measured in units called bits – or bytes. Bits are tiny pieces of data that make up a computing language. They are the DNA of digital information. Computers main form of communication is binary code. When talking about digital data or computer language we are referring to binary code. Binary code is a string represented by 1’s and 0’s. A combination of strings helps the computer to recognize and log images in a digital format. Essentially bits are read by computers and use strings of 1’s and 0’s to communicate digital information (Brain).
In digital photography, bits represent pixels. Most often, people associate more pixels as better quality photographs. Generally, this assumption is quite true – but to a point. Pixels are tiny colored dots that make up a digital image. It’s the smallest element in a display. Each digital photograph is comprised of millions of pixels. Usually, cameras are measured in megapixels (1 million pixels). Some cameras have the ability to produce higher quality images depending on how many megapixels it has (Photography 101). High-end cameras can produce images over 12 million pixels.
After the CCD/CMOS converts the light into digital information then it is stored internally to a memory card. Most cameras nowadays use flash-based media such as SD or CF cards to store their images (rtt). The larger the card, the more pictures can be stored. Typically cards are measured in gigabytes. Also the faster the card, the less dropped frames and images you will have. Card speeds are measured in megabytes per second and are organized in classes – which refers to the speed of the card.
After the images are captured to the card, they are then transferred to a computer. Photographers can now directly manipulate their images using programs like Photoshop.
Works Cited
Brain, Marshall. “HowStuffWorks “The Base-2 System and the 8-bit Byte”.” HowStuffWorks “Computer”. N.p., n.d. Web. 11 Apr. 2013. <http://computer.howstuffworks.com/bytes1.htm>.
“Cambridge in Color: A Learning Tool for Photographers.” Cambridge in Color: A Learning Tool for Photographers. Cambridge in Color, n.d. Web. 11 Apr. 2013. <www.cambridgeincolour.com/tutorials/camera-exposure.htm>.
“How Cameras Work.” ThinkQuest : Library. ORACLE, n.d. Web. 11 Apr. 2013. <http://library.thinkquest.org/28146/function.html>.
Johnson, Dave. How to do everything with your digital camera. New York: Osborne/McGraw-Hill, 2001. Print. Page 7.
“Photography 101.org – Camera Settings Explained.” Photography 101.org – Tips, Tricks, and Tutorials. N.p., n.d. Web. 11 Apr. 2013. <http://www.photography101.org/basics/camera_settings_explained.html>.
“SD Cards Explained.” SD Cards Explained. r-tools technology, n.d. Web. 11 Apr. 2013. <http://sd-cards-explained.articles.r-tt.com/>.
Digital Photography 