What is Exposure? Understanding its utility .
The Shutter Speed.
The Aperture
The Film Speed
These three things can make difference of the exposure.
In understanding exposure, you need to understand shutter speed. The shutter speed is a measure of how long the shutter stays open.
The aperture is an adjustable hole in the lens. It can open to allow more light in. Or it can close to become just a tiny hole, stopping so much light from entering.
ISO 100 was fine for everyday use in good light. But if the light levels dropped, you had to compensate by having a slow shutter speed, and a nice wide aperture.
