exposure - Why are my Nikon D5100 M Mode (Manual) settings reset for every shot whilst the camera pointing to the same object?

I've just noticed that whilst shooting with my D5100 using M mode settings reset after each shot.

Say, the camera is on a tripod pointing to an object. I've balanced out the exposure to a 0, aperture set to F/8 (this doesn't change btw) and the shutter speed is set to 1/15. I take the picture (camera hasn't moved) and the exposure level and the shutter speed have changed to some random settings (+2 EV exposure and 1/250 shutter speed - it's different every time though).

I've searched everywhere, but couldn't find an option that would allow me to save/lock my current settings providing the the image in the view finder doesn't change.

Ideas?

Answer

This behavior is caused by automatic exposure bracketing.

I've had someone with a Nikon D5000 behaving the same way in manual mode, and it turns out that automatic exposure bracketing caused this problem. My Pentax K-5 behaves the same way if the drive mode is set to exposure bracketing in manual exposure mode.

If this does happen to you again, make sure that bracketing is not set and disable it if it is. You do not need to reset the camera to factory defaults.