I became interested in photography in 1967 while I was in high school. I saved and saved and bought a Pentax Spotmatic w/ 50mm f1.4 lens and paid part of my way through college doing a variety of photography gigs as I acquired additional glass. Later I switched to Nikon in the 70's but...
Problem resolved- see update #8. ARGH! LOL!
Recently bought a D750 with four lenses: Nikon 24-70 f2.8, Nikon 85 f1.8G, Nikon 135 f2 DC, and Nikon 200-500 f5.6 VR. My background has been in Canon, Olympus m4/3 and some Fuji--never Nikon.
In fooling with the first three lenses- no issues but...