First of all, any glass put in front of the lens (or between the lens and the body) is an OBSTACLE - whatever good it does, it does the bad, too. So, use it ONLY if/when NEEDED (skylite, UV could have some positive impact, the "protector" - NONE). Even the UV and/or skylight often produce NO GOOD result, that is, do not really help to avoid certain problems related to different types of unwanted rays of light)... But, the protector is an extreme gimmick - sooner than later it will get scratched and by the time you notice it, you'll end up with the bunch of blurred pics... NOTHING can replace the lens cap.