Earthrise. On December 24, 1968, Apollo 8 astronaut William Anders took the first photograph of the Earth from lunar orbit. The photo became known as "Earthrise," and it was the first time human beings had ever seen the Earth from the perspective of another heavenly body.
Renowned outdoor photographer, Galen Rowell, called it the "most influential photograph ever taken."
The Overview Effect – A term coined by Frank White in 1987 describes the emotional sensation that many astronauts experience when viewing the Earth as a whole from the stillness of space. This view, according to the astronauts, radically changes your perspective and enhances your appreciation for the beauty and fragility of life on Earth. You feel tenderness towards her because she is so small against the backdrop of infinite space and so beautiful too. And you think of all the lives of animals and species and humans who’ve lived there and all the drama of life on earth, its splendor and travail, its suffering and joy. And you have to ask: “What is it all about?” And when you do ask that question you are confronted with a profound mystery. A mystery that no one can fully explain or understand, not one living person throughout the history of recorded time. For we are all caught together in the same net of life and time. And we don’t know why. Yet we feel this profound sense of gratitude, humility, and awe. -Reflections on the Overview Effect, Kim Ashley
Astronauts Speak – “The thing that really surprised me was that the Earth projected an air of fragility. And, why, I don’t know to this day. I had a feeling—it’s tiny, it’s shiny, it’s beautiful, it’s home, and it’s fragile.” -Michael Collins, NASA Astronaut, Apollo 11
“And a little later on, your friend goes out to the moon. And now he looks back and he sees the Earth not as something big, where he can see the beautiful details, but now he sees the Earth as a small thing out there. And the contrast between that bright blue and white Christmas tree ornament and the black sky, that infinite universe, really comes through, and the size of it, the significance of it. It is so small and so fragile and such a precious little spot in the universe that you can block it out with your thumb. And you realize that on that small spot, that little blue and white thing, is everything that means anything to you – all of history and music and poetry and art and war and death and birth and love, tears, joy, games, all of it is on that little spot out there that you can cover with your thumb…. And you realize from that perspective that you’ve changed, that there’s something new here, that the relationship is no longer what it was.”
-Russell Schweikart, NASA Astronaut, Apollo 9
One of the classes I teach is "Mastering Exposure and Focus." This class shows students how to adapt creatively to difficult lighting situations (exposure) and how to improve their skills in getting tack-sharp images (focus.)
In this blog, I want to define some key terms relating to exposure.
Exposure. The amount of light reaching the sensor based on four factors: the ambient light, aperture, shutter speed, and ISO. The ambient light is the light surrounding your subject.
Exposure Triangle. These are the three features on a digital camera that you control: aperture, shutter speed, and ISO.
Aperture. The opening in the lens that is similar to the pupil in the eye. Various aperture sizes are designated by f/stop numbers. For example, f/4 is a wide aperture opening while f/22 is a narrow opening. The aperture range on a typical lens looks like this: f/4, f/5.6, f/8, f/11, f/16, f/22, f/32. When you go from f/4 to f/5.6, you are doubling the amount of light on the sensor. This is called a stop of light. When you go from f/32 to f/22, you are cutting light in half.
Depth-of-Field (DOF). This is the range of sharpness within an image. Aperture sizes affect the DOF. Wider apertures, such as f/4 help create a shallow DOF, which is good for close-ups and portraits. Small apertures, such as f/16 or f/22, create a deep DOF, which is good for landscapes.
Exposure or Shooting Mode Dial. Advanced digital cameras offer a fully automatic shooting mode plus several creative modes: Program, Aperture, Shutter, and Manual. In Aperture Priority, for instance, you have creative control over DOF. Aperture Priority is designated on your mode dial as either "A" for Nikon or "AV" for Canon. In Shutter Priority, you have creative control over freezing or blurring action. "S" on the mode dial for Nikon. "TV" on the mode dial for Canon. "TV" means time value.
Shutter Speed. This is the amount of time your camera spends taking a picture. It's usually measured in fractions of a second. Advanced cameras offer a range of shutter speeds from 30 seconds to 1/4000 of a second or faster. You can freeze most action at 1/200 of a second. You can blur most action at 1/50 second or slower.
ISO. This measures the sensitivity of your sensor to light. ISO typically ranges from 100 to 6400 on most digital cameras. Here's the range given in full stops of light: 100, 200, 400, 800, 1600, 3200, 6400. On a sunny day, the ISO setting might be 100-200. At twilight, however, the ISO setting might be 800-1200. As you increase the ISO, the sensor becomes more sensitive to low light situations. Some cameras offer Auto ISO.
When you understand the Exposure Triangle and learn to master Aperture, Shutter Speed, and ISO, you will be able to create more compelling images.