For months I have had a problem with my D7000. At times I will take it out of the bag, mount a lens on it and go to shoot....but it will not focus at all. All switches on lens and camera are set to AF. The only thing that appears to fix it is rubbing my finger over the camera connections and lens connections. Then it "usually will work a few days. Problerm is annoying and keeps cropping up. Today the only way I could fix was slightly wetting my finger. It happens with ALL my lenses (18-200mm AF VR, 85mm 1.8 AFS, 70-200mm f/2.8 VR II) so I know it is not the lens. Any thoughts? Everything else works and all exposures are fine. Focus dead on "when" the AF is working.
This sounds very much like a problem with contacts. I've had this although with just a single lens. Removing the lens and remounting usually took care of it.
I think a more appropriate cleaning agent would be advisable. Try Radio Shack.
And, umm, (if this it is the contacts) this is a problem that requires both a lens and a camera to be involved. Kinda like unintentional pregnancy. Although one can be more at fault than the other.
The only thing that appears to fix it is rubbing my finger over the camera connections and lens connections Wow! Get a Q-tip and some CRC Contact Cleaner/De-Oxit and clean those suckers!! With lens contacts you
work in one direction over and over and over as you rotate the Q-tip. Rinse/repeat 'til no more black crap shows.
All your camera body contacts should be wiped monthly, a back and forth motion & tip rotation works best. This
should be part of everyone's normal maintenance, pretty surprised it's not common knowledge 10 yrs into DSLR's.
Thanks Trenchmonkey. I have been shooting Nikon DSLRs for all of those 10 years. Not professionally but still 10,000-20,000 images a year. This is the first DSLR I have ever encountered this problem on. I have had D700, D2X, D1, D200, D300 and a D40 in the past. Will give it a good cleaning. I just got back a D700 from Nikon service. Bought it knowing it needed a new memory card socket. Was not planning to keep it but might at this point. Got some beautiful available light shots at church today while we were having installation service for new senior pastor. Thanks again.
sassykoi wrote:
I am new to DSLR's and did not know this. Where can you purchase the CRC?
I would take a class in P-Chem before I used any liquid cleaner around a camera/lens. The high vapor pressure of the liquid will love to migrate to lens or sensor, IMHO
Look up PV=nRT That is a good start.
Where have we heard about oil on the sensor before?
Consider non-volatile cleaning. I can not recommend one as I have never had to clean a camera contact.
SweetMk wrote:
I would take a class in P-Chem before I used any liquid cleaner around a camera/lens. The high vapor pressure of the liquid will love to migrate to lens or sensor, IMHO
Look up PV=nRT That is a good start.
Where have we heard about oil on the sensor before?
Consider non-volatile cleaning. I can not recommend one as I have never had to clean a camera contact.
Yes, you are correct. I wouldn't shoot the crc on the contacts. it'll migrate all over the place and remove any lubricant it comes in contact with. Just shoot some into a glass and dab it with a q-tip and rub the contacts. It evaporates very quickly. If he is going to use something like crc, care has to used to only get it where he wants it.
Wow! Get a Q-tip and some CRC Contact Cleaner/De-Oxit and clean those suckers!! 
With lens contacts you