This is a single focal length lens... not a zoom. You zoom with your feet. What it does give you is an aperture opening of up to f1.8. This is what makes it possible to shoot in low light conditions without flash. It also gives you a shallow depth of field so that the major subject is in focus and the background is blurred. I use it with a D3300 which has the same capabilities as your D3400 and I am very happy with it. It is not the same as either of the zoom lenses that the camera comes with. These lenses only allow a maximum aperture of f3.5 or f4, which limits their low light capabilities and also their depth of field is greater.