So I am shooting a girls freshmen’s basketball game with settings with my Nikon D300 set at ISO of 1600 and Aperture at 2.8 in aperture metering mode using a Nikon 70-200 VR lens. I had taken a gray car reading and have been rattling of a number of shots when I noticed that my settings are changing.
My aperture keeps shifting to f/5.6. I turned the camera off and remount the lens and everything seems operated OK for a while and then begins to act up again. My D300 has never misbehaved EVER. I was a little concerned but kept focused on the task at hand. All in all, I got some good shots and really didn’t miss anything too important. Check it out here.
So what the deal? Is it the camera? Is it the lens? Is it going to be expensive? Yikes! Further investigation of the shots the misfired indicated that following reading.
Notice that there is an asterisk next to the f-stop. For Nikon D300 this indicates that a non-cpu lens is mounted. This clearly is not the case. So it appears to me that the lens and the camera are not commutating. This leads me to do some investigating. My current default non-cpu lense has the following setting.
When using CPU lenses, there are contacts where the lens and the camera body meet. This is the first failure point to be eliminated. Since the camera body seems to think there is a non-cpu lens it automagically defaulted to the non-cpu lens I had assigned. This explains why it kept changing to F/5.6.
So it is logical to insure that these contacts are clean. After searching the web for how to clean contacts, I came across this informative link. Cleaning the body contacts and Cleaning lens contacts.
I followed the guidance on the link for the most part and cleaned the contacts on the camera body and lens. I am happy to report that things are now operating correctly. What a relief!
So if you are experiencing a demonic changing f-stop, it is possible some simple maintenance could be in order.