That is NOT dust on the sensor. THAT is that damn annoying UFO that always abducts some drunk redneck!
You can tell because they are always out of focus!
This sounds like you have experienced this situation , don't even try to say the drunk redneck was a friend of yours!
It's dirt but it is a small speck of oil which happens when Nikon placed an excessive application of lubricant inside the shutter mechanism. This is a common issue that has been known with the D7000. You can easily clean it with a sensor cleaner.
That is NOT dust on the sensor. THAT is that damn annoying UFO that always abducts some drunk redneck!
You can tell because they are always out of focus!
This sounds like you have experienced this situation , don't even try to say the drunk redneck was a friend of yours!
Helene told me that Pete has never been the same since he experienced the UFO "probe". . . .