The focal length on a camera is dependent on the size off lens it has been fitted with. A small lens knows as a wide angle lens could be around 12mm however larger lenses knows as telephoto would be around 150mm.

There are two main ways to focus your camera, manual and automatic. manual focus allows you to use the focus ring on your lens to chose when and what you want to focus on. This is useful because it gives us more control over the image and allows us to focus on specific things. Auto focus is where the camera automatically focuses on a subject generally in the center of the frame however this can be changed. This function is helpful when we have time constraint for example if the subject is in motion.