Originally posted by dms Page 91 of the K-30 manual says "EV Compensation is not available in M or B mode."
You're right, it does. I hadn't read that before trying it. I guess the difference is that it doesn't adjust "on-the-fly" like it does in AV mode and others. However, it really does seem to have an impact on the decisions the green button makes. For kicks, I threw on an M 50 f/1.7, set the aperture ring to f/8 and set the ISO to 800 in M mode. Then I took three shots. 1st shot just pushed the green button and shot. Then hit the +/- button and dialed up +3, hit the green button and shot. Finally, hit the +/- button and dialed down to -3, hit the green button and shot. As you can see by the images below, the EV +/- setting seemed to impact the decision the green button made when it was choosing a shutter speed. With a manual lens and a set ISO, shutter speed was the only option left for the green button to tweak. Earlier my test was with a modern lens and both aperture and shutter speed seemed to change appropriately each time I pressed the green button and the EV +/- setting did seem to impact what it chose.
Of course, with the K-30 you can also set auto ISO while the mode dial is in M but the camera actually treats that as AV mode because that's really what it is.