The option you selected on your first screenshot is under display group, it's for the scene view you use in daz, not for how camera works. It simply turns on or of the box that helps you see where the camera focus will be.
The sliders you are looking for are under camera group settings, focal distance is indeed the one which lets you make things sharp or blurry, f/stop is the aperture and focal length is the zoom. Daz lets you experiment a lot with the settings, you are not limited like in real life where you need to buy telephoto lens if you want bigger focal length, or where aperture f/22 is basically the lowest opening (highest f number) you can use without a noticeable diffraction effect to take landscape photos that need to be sharp at both medium and long distance.