VR does NOT change exposure. It only allows you to hand hold your camera at 3 to 4 times slower shutter speed without getting motion blur. For example, if you need to use at least 1/200 sec with your 200mm lens to get a sharp image, you can change the shutter speed down to 1/30 or 1/15 sec with a corresponding change in aperture/ISO to maintain the correct exposure. Hope this helps you.
That is the manufacturer's marketing statement about VR. Actual results may vary!
WM