20 July 2011

Photography Basics

Susan Brannon
20 July 2011

How a Camera Works Made Simple

The word “photography” is French derived from the Greek language, in English it means “drawing from light”.   Photography is really all about light and how the camera works.
In a camera, light travels from the object to the sensor in film cameras.  The light goes through the lens to the sensor.

When you set your aperture inside the lens, that opens and closes depending on how you set it, little or lots of light will hit your sensor.  The aperture is controlled by “f stops” f2.8 is wide and f/19 is small. The lower the number, the more light will be let in. (Remember this and it will be of great help!) Once the light hits your sensor, and is absorbed and transforms into pixels.

The image that the sensor picks up is upside down and then flips it.

The shutter is what controls how long the sensor is exposed, the longer the shutter is open the more light can be absorbed onto the sensor. There are numbers that represent the speed of the shutter, 1/1000 of a second is fast and 3 seconds is slow. Remember, the lower the number the less light will be let in.  The amount of light absorbed by your sensor is called “exposure”.  There are two things that control the exposure, the shutter speed and the aperture.

In addition, you have film that has sensitivity to light; in digitals, it is your sensor that is sensitive to light.  The film speeds of the film (sensitivity) are called ISO.  A low ISO speed required longer exposures; a high ISO speed requires less time to give the same exposure. 

One might ask, “Why are there all these controls?  Can’t we just use one control to tell the camera how much light to let it?”  Well, The various controls allow you to control other aspects of an image.  A shutter speed can help to freeze the subject in motion; the aperture controls the depth of field and what is focused in your image.
Complicated?  All this means is that you must understand, how much light you need to expose to your film or sensor in order to generate the type of image that you desire.

*Tip: Remember:
Shutter Speed: The lower the number the less light
Aperture: The higher the number the less light
ISO:  The higher the number the more sensitive the film or sensor is to light.
Related lessons:
Aperture and f/16 Rule
Shutter Speed Basics

Depth of Field
Focused Bracketing or Photo Stacking 

No comments: