For your lens
f/2.8G AF-S DX
- f/2.8 = the maximum aperture size of the lens.
- A larger aperture lens will cost more than a smaller aperture lens. All other things being equal.
- You will also see something like f/3.5-5.6. This is a variable aperture lens, where the max aperture get smaller as you zoom the lens out. A variable aperture lens is cheaper to make than a fixed aperture lens.
- G = lens where the aperture is controlled by the camera. The lens does not have an aperture ring.
- I could not use a G lens on my old F2, as the F2 does not have a way to control the aperture.
- AF-S = Auto Focus, Silent motor. This is an electronic autofocus, vs, the mechanical screw drive AF-D lenses that Nikon used before.
- The AF-D lenses required an AF motor in the body. So a D3400 camera could not autofocus an AF-D lens, as it does not have an AF motor in the body.
- DX = DX crop sensor lens. The projected image from the lens will cover the smaller DX sensor, but will NOT fully cover the larger FX sensor. Because of this, DX lenses can be made smaller and cheaper than similar FX lenses.
A "pro" grade lens is generally made with better materials and made tougher. This costs $$$.
The pro zooms are the fixed f/2.8 (and now f/4) zooms vs the consumer/prosumer variable aperture zooms.
The pro gear has less compromises in the design. Image quality comes before convenience. The optics are better. And good optics cost $$$$.
The Nikon F mount is the same mount that has been used since the Nikon F in the 1960s.
BUT, and it is a BIG BUT, the meter coupling has changed over the years from mechanical (ears to AI) to electronic, and the AF has also changed from mechanical to electronic.
So while the mount itself has remained the same, the coupling of the lens to the body has not. And with that coupling change has come incompatiblities, that you need a compatibility chart to figure out. This chart can be critical if you use older film eara lenses with modern digital bodies. Even with digital, the new P lenses cannot be use with older digital bodies.