Aperture is the amount of light let into the lens which is measured in F/Stops. The F/Stops allow to control how much is going in – 1.4mm F/Stops lets a lot of light in while 50mm F/Stops will make it a pinhole shape.

Depth of Field is what’s in focus, in front and behind the subject. Deep depth of focus means everything is in focus however there is a small aperture. A shallow depth of field is only one thing in focus with a large aperture. If you want more focus you need a higher F number, but if you want a less focused image use a lower F number.