The whole technical aspect of photography is about exposure. To put it simply, how light is harnessed through a lens and projected as an image onto a film’s surface or a camera sensor to produce an image.
While the proper application of exposure control is not an end-all basis for a good photograph, it does benefit the photographer to know how an exposure is made and how you can control the exposure to produce the images that you want.
With today’s advancement of computer chips in cameras, it has become easier to achieve a “proper” exposure in most scenes that users will enounter.
The amount of presets in most consumer pocket cameras are so abundant, it has become quite tricky NOT to get a proper exposure in most cases with automated cameras. However, most camera users think this is some sort of computer “magic” that the camera knows what to do when you change your setting from “Beach” to “Fireworks” to “Winter”, for example.
The reality is, the camera manufacturer merely made some preset adjustments to the fundamental parameters of obtaining an exposure – namely, shutter speed, aperture opening, and film/sensor sensitivity! The uninformed user simply doesn’t know this.
Not knowing the relation of these three parameters will limit you to what the cam decides is right, you’ll end up being a camera operator without understanding why and how the equipment works.
As mentioned, exposure is based on three fundamental parameters:
Shutter speed – How long the shutter stays open to let in light.
Aperture size – How wide the aperture blades of the lens can open. The larger the opening, the more light can enter.
ISO/ASA – How sensitive the sensor is to light or how sensitive the film is to light. The more sensitive, the more light can be captured at a given time.
Let’s get visual with the explanation on the next pages.