I am new to Nikon (and NikonRumors) after 20 years with Canon. (I could not find a thread on this topic). I am using a D850 and two E type lenses, but want an ultra wide angle (zoom or not). What exactly is the difference between G type and E type lenses? Also, is the Tamron 15-30 f2.8 G2 equivalent to a Nikon G or E type? I assume so because it appears to not have an aperture ring?