I've experienced that same issue; intermittent black frames and loss of AF. It happened once while shooting a Downhill Mountain bike race where it was VERY dusty. Each time I was having trouble with focus (not focusing at all), I'd loosen the lens and rotate it back and forth on the body then lock it back in place which would get it working again.
I didn't notice the black frames until the end of the day when I was reviewing images. Out of several hundred, I had roughly 5 that were black. After that event I gave everything a good cleaning and haven't had that issue since.
Is it happening with all the lenses you mentioned, or just one in particular? When you said you cleaned the contacts, did you get the ones in the body as well?
I have had this happen once or twice while shooting a softball tourney. I simply removed the lens and cleaned the contacts and replaced.. Hasn't happened since. YMMV
Clean the contacts on both the body and lenses. The D300 seems to be more sensitive to dirty contacts. Is your firmware up to date? Last update was about a year ago, the summer 08 update seemed to fix the DBS.
Baywing wrote:
Clean the contacts on both the body and lenses. The D300 seems to be more sensitive to dirty contacts. Is your firmware up to date? Last update was about a year ago, the summer 08 update seemed to fix the DBS.
+1
Had similar problems last year but not since. Cleaned contacts and updated firmware.
Work got in the way today, but I will check the firmware and cards tomorrow and clean the lens contacts. The cards should be good...I bought them at local big box stores...
This happens to me every once in a while. I turn the camera off and on and it usually clears itself up. It only seems to happen to me when I'm using the Sigma 120-300 lens. Personally I don't think it's down to memory cards.