The sensor of my A77 was stained which gave me of skies with black spots from f8. By closing most was worse. Used with the Eclipse liquid sensor is reverted my own with a round trip that lasted 3 seconds. And more than hickeys on my photos. If you have any fears, videos on the net show the exact procedure. The hard part is overcoming his initial apprehension. Otherwise, it's fast, easy and the sensor is cleaned.