ARECONT VISION LENS4.0 / 4mm, 1/2", f2.0, Fixed Iris, 90° FOV

well hello today I wanted to talk of lenses fpv lenses little things are these let's go on in of your camera and there's two reasons I want to talk about this and the first is gonna sound a bit basic because I want to talk about the focusing and swapping of lenses and the reason I want to do this is I keep meeting people who the new pilots and they're flying with cameras that I found to be out of focus now one of the problems about being new is some of them just assumed this is like not a very good cameras like hey what can we use and yours looks really good and it's like it's the same one I've just twiddle my lens a bit to get in focus so I really wanted to discover how to focus because it only has to be a little bit off and it all goes with its soft then you just can't see as well and the other reason about swapping lenses is about what is the difference between like a 2.8 a 2.3 or 2.