SBrodsky Loc: Northern Colorado

Have a quick question. My go-to unit is a Nikon D700. Was out the last couple of evenings trying to get some Christmas Lighting displays. In manual mode, attempted to move sub-command (front) dial, to change aperture, but was stuck on 2.8. Came home and futzed with the Depth of Field Preview button, which when looking at the front of the camera and lens, is the one on the top left. That seemed to correct it, at least inside. Went back out again tonite, and the sub-command dial made some, but not all the changes I wanted, then it froze back to 2.8. Stayed at 2.8 in the other shooting modes as well. Quickly called a good friend, who has the exact same unit, and he suggested removing the lens, and re-inserting it. BINGO. Problem solved. At least for now. Am I on the right track? Do I need, e.g. to clean the bayonet contacts on the lens/camera front with a Q-tip and some alcohol? Or is there some other control that I may have accidently turned on, which defaults into this? Thanks

V2volk Loc: St. Louis area

Maybe you need to carefully clean the contacts as well.

TallTree

Use gray eraser to clean contacts, just be sure not to let "crumbs" foil the contacts!

SBrodsky Loc: Northern Colorado

UPDATE: Had trouble again last evening while on assignment for my newspapers. Pulled out my Nikkor 70-200 and it worked fine. Stopped by Mike's Camera in Boulder, CO today, and like a car that doesn't squeak when you take it into the mechanic, my lens was okay, even on several of their units, including a new Nikon 850. Sales rep advised to clean lens and corresponding camera contacts with denatured alcohol. Done. Knock on wood, I won't be lens shopping anytime soon. While there, looked at the new Sigma Art 2.8. 24-70 (Mine is an EX). It was sweet. Better be for $1200.

SBrodsky Loc: Northern Colorado

FURTHER UPDATE:Turns out this wasn't a command-dial and/or contact problem at all. The culprit: a couple of loose screws on the bayonet mount of my Sigma 24-70 2.8 EX. Upon closer examination, there were two small screws that were not fully tightened or which had come loose. Given the amount of times that this lens has been removed and reinserted, I'm not surpised. A few quick turns with a small screwdriver and KNOCK ON WOOD, it works as it should. Certainly saved me the $800+ or so for a new lens. And as long as my cameras (Nikon D700 and D7200) still work, there's no need to replace bodies, either.