I have a D7100 and was looking @ a nikon 18-300 af dx. will the tamron or sigma equiv lens give the full frame use as with the nikon?

I had the same issue with my d7100. Tried to follow all the instructions even on youtube, finally gave up and took camera and card to my computer guru. He understood the folder lingo and click click all worked.

T-33, dual cockpit, wrong wingtip tanks

I bought my 1st Nikon in 1965 and still have all those very heavy lenses. If I wanted, I could still use them on my d7100 as I have on my F3 and F5. I know not A/f but they are sharp.Not many brands can say that, new body new lens mounts etc.