Focus
There are 3 factors that effect whether an image is in focus or not. These are auto-focus points within the frame and the aperture.
Auto Focus: This must be switched on by the AF/MF button o the lens.
Focus Points: The focus points with in the frame can be set manually or left on automatic. You will see these re lights within the viewfinder that flash and make beeping sounds when part of an image is in focus.
Aperature: Having a wide aperture (e.g. f4.0) gives a shallow depth of field. A narrow depth of field (e.g. f22) gives a large depth of field.
Bellow I have used a photo of my jeans as an example of a shallow depth of field:
Movement
How much movement blur we can achieve within our image depends on the shutter speed we set on the camera.
A slow shutter speed will exaggerate movement within your shot and cause light trials. It also picks up the shakes of the camera. Below is an example of a slow shutter speed being used to capture the movement of a car, when everything else is relatively crisp.
A fast shutter speed will freeze movement. Below is an example of this. The car below was going the same speed as the one above.
Exposure
How light or how dark an image is depends on 3 factors: The shutter speed, the aperture, and the exposure compensation.
Shutter speed: A slow shutter speed lets in more light than a fast shutter speed.
Aperture: A wide aperture (e.g. ff4.0) lets in more light than a narrow aperture (e.g. f22).
Exposure compensation: How mud extra or less overall light we give to an image to make it brighter or darker.
The photo below was taken outside on a bright day. The shutter speed was very fast shutter speed stopped too much light coming into the photo, and I had a slightly wide aperture to have a bit of depth of field.
Quality
The quality of the image depends on two main factors. The ISO and the file type.
ISO: 100 ISO is least sensitive to light but the best quality, whereas 1600 ISO is the most sensitive to light but the least quality (noisy).
File type: The file type describes how much colour information and resolution the final image has.
White balance: This adds a warming (amber) or cooling (blue) colour filter to the image in order to balance out the whites with diferent light sources. This can cause problems when shooting in diferent environments. a cool (blue) filter will make the photo look too blue and cold, as seen below.
