I want to thank author Ben Long for writing an amazing book called “The Canon EOS Digital Rebel T1i/500D companion”. I feel like I’ve been learning so much about the theory of photography and I appreciate his writing style and descriptions. Because the book applies the theory with the same camera I own, I find that learning is about photography is so much more appealing.
The 3 Exposure Mechanisms
The shutter is positioned just in front of the image sensor. When you are using a very quick shutter speed you are going to let in less light then if you use a longer shutter speed.
The Aperture is positioned at the end of the lens. Much like the iris in your eyes the wider it gets the more light.
The ISO is a standard for measuring the sensitivity of the film. Digital vendors adopted the standard for the sensitivity of a digital image sensor. The image sensor measures the voltage on the sensor’s surface. ISO amplifies these voltages.
Stop is a measurement of light. More specifically a stop represents a doubling of light.
The “F-stop” is a measure of the ratio of the focal length of the lens to the size of the aperture. It might seem ass backwards but a larger F-Stop means that there is a smaller opening in the lens.