So I was experimenting with Aperture Priority and depth of field. The F-stop rating on a lens is how open the aperture can get. The lower the f number, the wider open it can get. My airshow lenses tend to be around f/3.5-f/4. My latest lens is at f/1.8, which means it is wide open at f/1.8. That means it let in a lot of light. It will definitely make the lens "faster", but it also has a trade-off. The low f-stops lets you pull in light better, making it great for low light photos and catching well lit action with high shutter speeds. What you end up with at f/1.8 is a shallow depth of field. What that means is that your area of focus, or foreground, will be nice and crisp, while the background will be out of focus. This is great for portraits and close ups because it draws the viewers eye right to what you were focusing on when you took the photo. But you also have to be cautious with close-ups as there will definitely be portions of uneven surfaces in better focus that others.
As you go up in f-stops, more of the background comes into focus. The maximum f-stop that the new lens will go is f/22. At f/22, you get a deep depth of field and the entire frame will be in focus. Here are some examples, with their f-stop ratings in the photos.