Overexposure problem with Kenko extension tubes on D7000

Until recently, I have been successfully using Kenko extension tubes in combination with D7000 and Nikkor 105mm macro lens. Recently, all photos taken with the extension tubes are very overexposed (at least 4 stops). Focus is still working. I have no performance issue when the extension tubes are not in use. Any idea what could be causing this sudden problem?

Thanks
Steve

The first thing that comes to mind is exposure compensation. Did you check if you not accidentally set it to overexpose?

No its not compensation. In fact, I can roll off the compensation completely, and it the images are still overexposed.

Assuming the Kenko allows communication with the lens, there might be a difference between the aperture the lens is actually using and what the cam thinks it will be using. If that's the case your meter will give a different readout than it should.

It's a guess since all works well without the tube. When the metering and exposure compensation are correct, there isn't much left which can cause an overexposure problem besides the aperture in use. Did you try cleaning the contacts?

Or something might prevent the lens from closing down far enough. You can try shoot wide open and see if that is overexposed. If not, something in the tube might cause the issue.

Good suggestions - Let me try those and get back to you...thanks!

are u using all 3 rings at once together? I had teh kenko rings and at times the camera lost communication. there was a little flex at the end of the lens from the weight when I used all 3 rings. try cleaning the contacts and try getting the setup to OE again, then try to press the lens back towards the camera and take a quick shot to see if it made a difference. good luck

I remember having such a problem because the little aperture tab was sticking, preventing my lens to close it's diaphragm. To test for this, try exposing with aperture fully open and then one at let's say f-8. If the one fully open exposes correctly and the f8 or f11 one is over, you've found the culprit. You can also remove the lens and extension tubes from the camera and while working the tab see if the diaphragm opens and closes. I suspect this could be your problem. For me, it only happened with the medium extension tube and with only one lens. The smallest and longest ones did not create this problem.

Let us know what you find.