I have the D750 as well and always use the menu to format the cards. For off loading photos I plug in a usb cord on the side of the camera. I never take the cards out of the camera.
I grew up in Towson...not far from Hunt Valley. Those pictures really bring back memories of the Hunt Cup Races. Beautiful area. Thanks for sharing your great shots. Tom...
You ask them the next time they bake a cake or fix a wonderful dinner would they be happy if the guest say "That cake or dinner was wonderful....you must have one great oven or stove!" That might get the point across.
Mark I took that same trip last year. We have taken quite a few Caravan trips. Really enjoy them. You can see some of my pictures from the trip on my personal web page. Or click on the link below.
I had a problem like that...... and the cause was the lens not being fully attached and locked on. I removed the lens and then put it back on camera and everything was fine after that.