Principles of Exposure: ISO and Noise

Part A:  Produce 4 images showing the range if ISO settings from low to high

                          

Part B: Exposure

Aperture: 

The aperture (opening) of a camera is refers to the series of blades that open and close over each other to control the diameter of the lens, and hence, the smaller the aperture the less light is let in the lens (and vice versa). 

As well as controlling how much light is in an image (exposure), the size of the aperture can be used to change the 'depth of field' in an image. The depth of field refers to how much of the image is 'in focus' or crisp. A shallow depth of field means that only a small portion of the image is in focus and the rest of the image (in front of and behind the subject of the image) is blurry. This is achieved by using a large aperture (light is refracted more farther from the centre of the lens). Conversely, a large depth of field refers to a greater area of the picture, around the subject, being in focus. It is achieved by using a small aperture (only near the centre of the lens, which is less curved, is being used, and so there is less refraction).

Large Aperture

Small Aperture

Shutter Speed:

The shutter speed of a camera refers to how fast the shutter opens and closes. The mirror behind the lens reflects the light through the viewfinder. When a photo is taken, the mirror is flipped out of the way to expose the film to the light of what the camera is pointed at. How fast the mirror is flipped out of the way and returns back to its resting position is what we know as "shutter speed". Obviously the longer it takes for the mirror to return to its resting place, the longer the film is exposed to the light and the brighter your image will be. Conversely, the faster the mirror is flipped back to its resting position, the less time the film is exposed (to the light) and the darker your image will be.
Shutter speed controls an extra dimension, when shooting things in motion: motion blur.
To eradicate the motion blur in an image, you must use a fast shutter speed. This is because the faster the image is taken, the more likely it is to capture the object mid motion (when it hasn't moved a great very much in the time the photo is taken). So your shutter speed should be proportional to the speed of what you are photographing (if you want to their to be no blur).
If you do want their to be motion blur, you can control how much blur, by making the shutter speed slower than your object in motion. How much slower you make it (the discrepancy between the speed of your object and your shutter speed) will dictate how much blur there is.

Slow shutter speed

Fast shutter speed

ISO

The ISO is the standardized industry scale for measuring sensitivity to light. Changing the ISO on your camera changes how sensitive your camera sensor is to light. A high ISO is useful for dark conditions, however it should be the last principle of exposure changed to increase exposure, because a high ISO sometimes produces a grainy effect on your photograph called "noise", and this tends to be considered undesirable.
Every time you change one element of the exposure triangle, the other elements are affected. 
In the example below, the ISO is being increased in each portion of the photograph. However, the overall exposure remains the same throughout the multiple images of the same thing. Each change in the ISO is equal to one F-stop (change the exposure by a factor of 2). Therefore if you increase the ISO by one F-stop then the aperture or shutter speed needs to be decreased by one F-stop so that the overall exposure remains balanced.