The Basics of a Camera
Photographic technology advances
quickly. The last 150 years have been a nonstop parade of change as we've moved
from chemical-based imaging technologies to current digital offerings. Along
the way we've also gotten, automatic focus, artificial lighting, faster
performance, and much more. Through it all though, the basics of the camera
have not changed. It may sound strange but at a fundamental level there's no
difference between your current digital camera and the earliest cameras of the
nineteenth century.
All cameras, even your
cellphone camera have the same basic components. They all have a light proof
box. This holds the photosensitive material that will record an image and it
has to be light proof because you're trying to capture and record light, so you
can't have any extra light around. Most cameras also have a lens. This is a
piece of material that gathers light that's bouncing off of your subject and refracts
or bends that light to focus it onto the light sensitive material that's
sitting in your light proof box.
ISO, Shutter
Speed and Aperture
It is difficult
to take good pictures without having a solid understanding of ISO, Shutter
Speed and Aperture ---the Three Kings of Photography, also known as the
“Exposure Triangle”. While most new DSLRs have “Auto” modes that automatically
pick the right shutter speed, aperture and even ISO for your exposure, using an
Auto mode puts limits on what you can achieve with your camera. In many cases,
the camera has to guess what the right exposure should be by evaluating the
amount of light that passes through the lens. Thoroughly understanding how ISO,
shutter speed and aperture work together allows photographers to fully take
charge of the situation by manually controlling the camera. Knowing how to
adjust the settings of the camera when needed, helps to get the best out of
your camera and push it to its limits to take great photographs.
A quicker
summary of the Exposure Triangle as a refresher:
- ISO– the level of sensitivity of your
camera to available light. It is typically measured in numbers, a lower
number representing lower sensitivity to available light, while higher
numbers mean more sensitivity. More sensitivity comes at the cost though,
as the ISO increases, so does the grain/noise in the images. Examples of
ISO: 100, 200, 400, 800, 1600.
- Shutter Speed– the length of time a camera shutter is open to expose light into the camera sensor. Shutter speeds are typically measured in fractions of a second, when they are under a second. Slow shutter speeds allow more light into the camera sensor and are used for low-light and night photography, while fast shutter speeds help to freeze motion. Examples of shutter speeds: 1/15 (1/15th of a second), 1/30, 1/60, 1/125.
- Aperture– a hole within a lens, through which light travels into the camera body. The larger the hole, the more light passes to the camera sensor. Aperture also controls the depth of field which is the portion of a scene that appears to be sharp. If the aperture is very small, the depth of field is large, while if the aperture is large, the depth of field is small. In photography, aperture is typically expressed in “f” numbers (also known as “focal ratio”, since the f-number is the ratio of the diameter of the lens aperture to the length of the lens). Examples of f-numbers are: f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8.0.
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