In examining how photography works, we will start out by looking at how light creates an image. This posting continues our examination of some of the concepts and elements that combine to produce memorable photographs. We hope you will join our exploration of this exciting phenomenon and that it will help you become a more skilled photographer. We also hope that it will encourage you to take more photos, especially of your growing family. It is great to look back over these photos as you enter your golden years and reflect back on your growing family. GLB
“No photographer is as good as the simplest camera.”
— Edward Steichen
“A photograph is memory in the raw.”
— Carrie Latet
“I hate cameras. They are so much more sure than I am about everything.”
— John Steinbeck
“There are no rules for good photographs, there are only good photographs.”
— Ansel Adams
“I think a photography class should be a requirement in all educational programs because it makes you see the world rather than just look at it.”
— Author Unknown
“Every time someone tells me how sharp my photos are, I assume that it isn’t a very interesting photograph. If it were, they would have more to say.”
— Author Unknown
“Perishability in a photograph is important in a picture. If a photograph looks perishable we say, ‘Gee, I’m glad I have that moment.’ ”
— John Loengard, "Pictures Under Discussion"
“There will be times when you will be in the field without a camera. And, you will see the most glorious sunset or the most beautiful scene that you have ever witnessed. Don’t be bitter because you can’t record it. Sit down, drink it in, and enjoy it for what it is!”
Drawing with Light: Controlling the Process?
As we continue our exploration of “Drawing with Light”, we will look at some general issues related to capturing an image and determining the most appropriate exposure. You need to remember that many things must come together to create a photograph. We need light, of course, but that light must be passed through a lens to focus the image, the aperture and shutter speed to control the exposure, and the sensitivity of the sensing media (film or digital sensor). We will start that exploration in this posting and continue exploring these factors in the coming weeks.
The Photographic System
The Photo Head web site documents three basic elements of the photographic system. Essentially, we need to control the light passing through the lens and camera system and landing on the photographic sensor, either film or a digital sensor. Let’s look at the basics of combining these elements to create an image.
Light… In order for an image to be captured on film, it must be exposed to light. In photography, it is important to be able to measure light. Too much light can ruin a photograph, and so can too little. Light can be measured and controlled by the brightness and by the duration of the light passing onto the Capture Medium.
Camera… Cameras come in all shapes and sizes. Three things all cameras have in common are a lens, an aperture, and a shutter. By adjusting the aperture ( F-Stop ) and shutter settings (Shutter Speed), you change the amount of light that falls on the film or digital sensor.
- The Lens:
The lens contains elements that work together to focus the light on the sensing medium. The quality of the glass and workmanship of preparing these lens elements determines how well these elements work together. In addition, the better lenses use special coatings on the lens elements to prevent light reflection and scattering.
- The Aperture:
The amount of light that passes through the lens to the sensing media (film or sensor) is determined by a set of overlapping leafs that change the size of the opening through which the light will pass. The larger the opening, the smaller the f-stop, and less time that will be required to create your image.
- The Shutter:
The length of time that the light is permitted to fall on the sensing media (film or sensor) is controlled by a shutter mechanism that controls the duration of the exposure. The longer the shutter allows the light to pass through to the recording media, the more the media will be exposed.
Capture Medium… Once the light has passed through the lens, the aperture, and the shutter, it will activate the sensing media. This may be film (coated glass or plastic carrier) or a digital sensor. In either case, the degree to which the image is recorded depends on the amount of light hitting the medium.
Film reacts to light. The more light you give to it, the brighter the image will be. You can buy all types of film for your camera, and they will all have a FILM SPEED. "Fast" films are more sensitive to light than "slow" films. Only the film is exposed in the camera, the image is activated and fixed on the film in the traditional darkroom.
- Digital Sensor:
The digital sensor reacts to light and records the amount of light in digital signals. The more light you give to it, the brighter the image will be. Different cameras have sensors that are different sizes and sensitivities. Unlike film, the digital image must be processed in the camera and stored on some long lasting medium, such as Compact Flash, Secure Media, or other types of digital storage. These data are then processed by a computer into a finished image.
Output Print… Once the image has been stored on the media and processed in the darkroom (regular or digital), it is ready to create a photographic print. This printing process may be done either in the wet, traditional darkroom or on a digital printer.
Determining the Exposure
The amount of light that will give you a proper photo is jointly determined by the aperture (amount of light admitted), the shutter speed (length of time the light is admitted), and the ISO (sensitivity of the sensing media). Varying any one of these factors will also affect the settings on the other two. The goal is to produce a combination of settings that gives you the image that you envision from the scene while also providing a “good” exposure. The following are some examples of different types of shots and the settings associated with those photos. These included here, but can be found on the Digital Photography School (see below for the reference). Take a look at these examples:
- High speed is needed to freeze action
- Use Shutter Priority
- Set shutter speed to 1/800sec
- The light meter sets the aperture to f10
- If under exposed, change ISO to compensate – ISO: 400
- An artistic narrow depth of field is desired
- Use Aperture Priority
- Set aperture to f5.6
- The light meter sets the shutter to 1/160sec
- If under exposed, change ISO to compensate – ISO: 100
- Ambient light is too low to accurately meter
- Use full Manual
- Set aperture to suit scene, erring to wider – f11
- Set a long shutter speed to light meter’s best guess – 20sec
- Set ISO to lowest possible for correct exposure – ISO: 100
- Take a test shot and adjust settings if the light meter got it wrong
Digital Photography School Web Site: The Light Meter…
Photo Head Web Site: Crash Course in Photography…